Those are still slow as shit, do you own research. Micro SD Cards are an incredibly dated format it doesn't matter who makes the card. 150MB/sec (and you don't even get that speed) in today's day and age is laughable. 

Nintendo is probably going have to change something because if the Switch 2 has more RAM than the Switch 1 (which is almost 100% a given), the loading times that are already pretty bad on the Switch are going to get worse if you just stick to slow ass SD Cards and flash storage from 2010. 150MB/sec to fill an 8GB main memory would take 53 seconds, that's absurdly slow, if the Switch 2 has 12GB or 16GB it's even worse. 

Even UFS 2.2, which is ancient and dirt cheap used in budget smartphones for the market in China/India is way faster than an SD Card or the current Switch cartridges. I think Nintendo will change that up to faster flash storage. UFS 2.2 is 1200MB/sec versus an SD Card, even a more expensive "pro" SD Card tops out at like 190MB/sec. 

I can't see Nintendo sticking with the current data speeds they have now, so if the Switch 2 uses even dirt cheap, old ass UFS 2.2, that's going to be a massive speed boost over the Switch 1 flash storage which was already faster than SD Cards. In layman's terms, take a look at this loading time:

(video)

For Switch 2, even using UFS 2.2 (again a very dated/cheapo flash storage), that loading time for the internal storage would easily be 5x-8x faster, so like the whole point of "well you can just buy a cheap SD Card!" doesn't come close to telling the whole story. An SD Card is slow as fuck and while it can (barely) keep up with the Switch 1's internal storage, Switch 2 will almost certainly destroy an SD Card in a comparison like above, so in your scenario you claim the person who bought the SD Card was super smart, but they'll be sitting waiting 40-60 seconds waiting for their game to load, while if Switch 2 uses any kind of modern flash storage ... they will be playing that same game within 5-8 seconds if that. Again, you get what you pay for, SD Cards are cheap for people who don't have money, but that's about it. A Switch 2 with more internal flash storage even at 1200MB/sec is going to blow the socks off any SD Card and would easily be worth $50 more going from 64GB to 256GB, that's bordering on a steal frankly. 

All this sounds like Nintendo would have to follow a PS5-like solution where the internal storage is small in comparison to the size of the games and a constant deletion and reinstallation of games is mandatory. People buy HDDs as external storage for the PS5 to keep their games on, then have them be copied over to the SSD from which they play them.

And in this case it would once again be pretty pointless to shell out money for more internal storage for the people who need a lot of space to begin with. They require external storage in any case, so the cheaper console SKU remains the smart way to go.

Sure you can get a junk Micro SD Card for $50 with a lot of storage, but that's going to be a crap 100-170MB/sec card that's slow as molasses. Just like you can get an old regular fat HDD with 4TB and declare yourself a genius because you have way more storage than the NVMe drives Sony and MS sell for the PS5/XSX. There's just one problem, your drive is a turtle by comparison. 

Nintendo could easily get UFS 3.0 or 3.1 speed internal flash storage, which can have up to 2100MB/sec read speed, it will blow any SD Card out of the water. And UFS 3.0 isn't some magical new or exotic technology, it's just the standard flash memory that's in hundreds of millions of Android phones and tablets already. And UFS 3.0 is the *old* standard from 2018, the new Android devices use UFS 4.0 which is double the speed, so Nintendo would likely be getting the 3.0/3.1 dated version for a laugher of a cost. 

If Nintendo were to offer it, I think plenty of people would rather pay the extra $50 and have the higher speed internal storage. Relative to what you pay to go up in storage for say an iPhone or iPad, getting double or quadruple (lol) the amount of high speed internal storage that's way faster than an SD Card for only $50 more is not bad at all. Also a lot of those cheap SD Cards have high failure rates and don't actually even hit the low end speed they claim, seen plenty of "150MB/sec cards" Micro SD cards that when tested are only reading at 80MB/sec if you're lucky ... you get what you pay for. 

UFS flash storage has other big advantages over older flash storage too, it's smaller and consumes less battery power. 

Or they could simply get a M.2 SSD if they want higher speeds. A small 256GB M.2 2242 costs just below 20€, 25€ for the even smaller 2230 format. Also, they both come with 2000MB/s second read and ~1000MB/s write. For 30€ you're already able to get a 480GB SSD, so why not go this route for extendable storage?

Also sure, Android Phones have the capability for UFS 3.x - but their chips can't keep up with that, as evidenced whenever you're getting some lengthy loading screens. UFS speeds are highly hypothetical and just like SSDs need multiple chips to achieve their full potential. 256GB SLC would be the absolute minimum fur UFS3.x to even make a difference over past standards - but at the same time, you can get cheaper 500GB MLC with similar speeds. In other words, going UFS 3.x and less than 500GB would be a waste of UFS. At that point, I don't think Nintendo would create another storage tier anymore.

Those are still slow as shit, do you own research. Micro SD Cards are an incredibly dated format it doesn't matter who makes the card. 150MB/sec (and you don't even get that speed) in today's day and age is laughable. 

Nintendo is probably going have to change something because if the Switch 2 has more RAM than the Switch 1 (which is almost 100% a given), the loading times that are already pretty bad on the Switch are going to get worse if you just stick to slow ass SD Cards and flash storage from 2010. 150MB/sec to fill an 8GB main memory would take 53 seconds, that's absurdly slow, if the Switch 2 has 12GB or 16GB it's even worse. 

Even UFS 2.2, which is ancient and dirt cheap used in budget smartphones for the market in China/India is way faster than an SD Card or the current Switch cartridges. I think Nintendo will change that up to faster flash storage. UFS 2.2 is 1200MB/sec versus an SD Card, even a more expensive "pro" SD Card tops out at like 190MB/sec. 

I can't see Nintendo sticking with the current data speeds they have now, so if the Switch 2 uses even dirt cheap, old ass UFS 2.2, that's going to be a massive speed boost over the Switch 1 flash storage which was already faster than SD Cards. In layman's terms, take a look at this loading time:

For Switch 2, even using UFS 2.2 (again a very dated/cheapo flash storage), that loading time for the internal storage would easily be 5x-8x faster, so like the whole point of "well you can just buy a cheap SD Card!" doesn't come close to telling the whole story. An SD Card is slow as fuck and while it can (barely) keep up with the Switch 1's internal storage, Switch 2 will almost certainly destroy an SD Card in a comparison like above, so in your scenario you claim the person who bought the SD Card was super smart, but they'll be sitting waiting 40-60 seconds waiting for their game to load, while if Switch 2 uses any kind of modern flash storage ... they will be playing that same game within 5-8 seconds if that. Again, you get what you pay for, SD Cards are cheap for people who don't have money, but that's about it. A Switch 2 with more internal flash storage even at 1200MB/sec is going to blow the socks off any SD Card and would easily be worth $50 more going from 64GB to 256GB, that's bordering on a steal frankly. 

All the cards on that video were UHS-I or lower. The switch should be able to use USH-II and USH-III, Should it not?

Even UFS 2.2 is going to be considerably faster than the eMMC 5.1 the Switch 1 uses now and way faster than an SD Card though. Android phones have a lot of bloatware too and Switch 2 probably will also have LPDDR5 RAM (pretty fast) which will help utilize that hypothetical UFS speed better, not all Android phones have that.

Would I like M.2 SSD and all that jazz ... sure, but I think it would make the system too expensive and/or take money away that could spent on the chipset/RAM, which I think are more important. 

I think UFS is probably the best compromise. It's cheap and widely available and faster than the current Switch or SD Cards. eMMC is too slow for a system that's going to have a large increase in system RAM and larger game file sizes, SD Card is even worse.

If games like Zelda: ToTK already have like load/wait times of 47 seconds to get into a game, I mean you're going to be seeing 1+ minute waits on Switch 2 without a change, which is kind of hilarious for a company that basically handed over the stationary home console market to Sony because they were that adverse to like 10 seconds of loading back in the day. 

You don't really need something as expensive as the PS5's hyper fast internal storage. Sure it is nice, and actually makes more sense for a portable machine, but Sony is also using that speed to do things like using the SSD as almost like a RAM buffer/pool in some games, since it's so fast it can operate almost like system RAM. I'm not even sure how many games even use that but that was their idea. 

Nintendo will easily be able to get something many times faster than the existing flash memory in Switch 1 without needing a solution like that. 

Flash storage speeds in mobile devices have come a long, long way since 2015-16 because of all the competition in the smartphone space, as I said Nintendo could use something cheap like UFS 2.0-2.2 flash storage, but even UFS 2.2 can give you like 800MB-1000MB/sec, the current Switch internal flash storage is probably around 100-120MB/sec, so that would be several times faster.

UFS 2.0-UFS 2.2 is what's used in no-name budget smartphones, so we're not talking about bleeding edge tech here at all, it debuted I think in the Samsung Galaxy S6 ... which is a phone from 2015, today no flagship phone uses it because UFS 3.0, UFS 3.1, and now UFS 4.0 are available. 

EDIT: The Switch 1 uses eMMC 5.1 internal flash storage it looks like, ... which is what smartphones used to use like pre-2015, you can see how much faster even UFS 2.1 is here (keep in mind an SD Card is slower than even eMMC 5.1):

(video)

Your post doesn't address how internal AND external storage will look like on Switch 2. But that's crucial when even your hypothetical 256 GB Switch 2 SKU has nowhere near enough space for people who need a lot of space for their games.