Digital is a dead end. With physical, if you have the gear, you can make legal backups long after it's cost efficient for the publisher to keep hosting the game online. 

I still prefer to own physical copies of my games; I actively enjoy having a collection of boxes with actual game cards in them, and I don't want to fill up my Switch's SD card and have to buy another one, I'd rather the one I'm using now lasts me the system's lifespan. (Which it should do, after 2 years of using a 256GB card I still have 220GB spare plus 3GB spare on the Switch's internal memory)

You are referring to buying access. I am referring to playing access. Normally if you own a game digitally you can still play it regardless if its been taken down from the store.

The same argument can apply to you when buying old physical games, unless you Ebay, you can no longer buy old games.

Not all my physical media works and i own 100s of games, however i own over 1000+ games on Steam alone and they all work, and some have been taken down from the store to purchase.

Modern games still require online access and accounts to play so phyiscal is basically useless with some games only having half the content while the other half has to be downloaded. Its nice to have the case to look at but unlike the 80s and 90s, physical is basically digital anyway.

Apparently the PS4 version is 38.69GB and the Xbone version is 36.78GB, but given that the textures and other assets will have to be reduced a lot to run on Switch in the first place, it should be possible to fit it on a 16GB card, especially as we've seen other games ported from PS4 to Switch reduced massively in file size.

I'm fine with a 4-6 GB install required after the card. It's not ideal, but at least we're getting most of the game stored for us - rather than shelling extra for another (or bigger SD). In a best case scenario, we could get a 32GB card with the entire game on it - Witcher 3 style!

The audio compression would probably be terrible if they did. Maybe we'll have those fabled 64GB cards by the time the Switch Pro/2 arrives...

Plenty of games are "locked" behind online access and thus were rendered unplayable.
https://www.funkidslive.com/news/full-list-games-affected-miiverse-closure-nintendo-announces-closure-miiverse-social-network-november-8th-2017-making-games-unplayable/#

Sure. But the difference there is that if the NAND/HDD fails (Which is a matter of when not if!) you loose your entire games library in one fell swoop. - That doesn't happen with Physical.

You see NAND, especially QLC and TLC NAND found in MicroSD cards and internal storage of the Wii/WiiU/DS/3DS and so on, isn't designed for "cold storage". - We are talking about POSSIBLE data retention in terms of weeks here, not years.
https://www.anandtech.com/show/9248/the-truth-about-ssd-data-retention

NAND isn't designed for cold storage.
Mechanical Hard Drives fair a little better, but they don't do so well with shock loads.

All my Physical media works.

I can even take a game from the 80's and run it on my PC just fine.

Again, there have been PC distribution stores such as Desura which have closed, which means you can't re-download your digital games if you loose your data, can you guarantee that Steam will be around 40 years time? Physical copies will.

In 2010 GOG.com did a "fake closure" which scared many PC gamers into thinking that they were going to loose the ability to redownload their titles. - What if it was a legitimate closure?
https://www.pcgamer.com/gog-com-apologise-for-hoax-closure/

The big difference is if the online store no longer exists, you cannot redownload your game if your device fails or looses data, you can just drop your physical copy into a different device and get started again.

You can work around the loss of online connectivity for the most part. - You can still play OG Xbox games online for example, despite Xbox Live being non-existent, you just cannot download new titles. Yay Physical.
https://www.teamxlink.co.uk/

And you are right, that Physical is starting to rely a little heavier on digital distribution, which absolutely sucks, generally when that happens there is a bit of a community uproar and some developers are taking note.

They are probably doing full lossless 7.1 Audio.

Compressing it down via your usual FLAC codec with a decent enough bitrate @5.1 would be sufficient for most users I would think.
Generally if you want the best visuals and audio fidelity, Nintendo consoles aren't the platforms to opt for to start with and most tech-enthusiasts would understand that.

That's weird, when I googled it kept telling me it was 38GB.

If it's 20.5GB then getting it on a 16GB card without an install should be a piece of cake.

Heck the Crash N.Sane Trilogy is 20GB on PS4 but just 5.2GB on Switch.

Not disgareeing with you, however my point before is nothing last forever. The mentally of owning physical games because it last forever is not true as everything has a life span especially media formats.

I cannot speak on behalf of console business models as there main strategy is to close and move on to there next product basically with the mentally of "upgrade or be left behind". However I am quite confident that Live and PSN are adopting a similar approach to Steam this gen which will carry onto there next products etc unifiying there eco-systems into one big platform. If someone is buying games on a not-so-well establishment than closures are more than likely to happen eventually.

Hardware is also likely to fail on gamers over time and considering Physical media is very reliant on hardware this only makes physical media more likely to have issues. Games can be scratched and eaten by disk drives, old cartridge style games do deteriorate over time aswell unlike Digital. Most of my Atari 2600 games barely work but if they were digital they will work every time like they were brand new. That's basically my point. Digital can actually last you longer than phyiscal if the game remains on the store front and like I mentioned before, its incredibly rare that a game you brought on a well known establishment like Steam, Live and PSN will be taken down.. I know there have be one offs here and there on those platforms however again its the only issue you have to worry about with digital. And if they did take the game down and you brought it, you can actually complain and claim a case with your digital receipt.

Like I said before, my Steam games all work like there brand new while my Atari, NES, PS1 and SNES games struggle, some work fine, some have been damaged over the course of time and some clearly don't work at all. I own Warhammer Online collectors edition and that games server has been closed, with the disk or not the game wont work period. So if you are in the business to collect, than physical makes sense but if you are in the business for last ability than choose your poison because both have advantages and disadvantages BUT I say Digital have very little disadvantages than Physical and I say this as a 15 year Steam user.

Not saying Physical lasts forever.

Console business business model is irrelevant. You can speculate on "possibilities" all you like, we either base things on evidence or historical precedence.
And plenty of console online networks have been shut down.

How long until the PS3 network goes under?

The Wii online store was an "establishment" that should have been mildly successful considering the size of the user-base, but didn't last as long as the Xbox 360 or Playstation 3's networks. Go figure.

Correct, hardware is likely to fail on gamers over time. But with Physical you aren't tying your ENTIRE game collection to that SINGULAR device.

You can bring your physical games over to the next system... Or even to the next system. (I.E. PS1 games on PS2, Xbox games on Xbox 360, Wii on WiiU and so forth.)

Fact is, Physical games have outlasted digital every single time if we are to base things on history, all my SNES games work fine today, I just replaced the batteries.
All my Nintendo 64 games work fine today.

All my OG Xbox games work fine today.

All my PS2 games work fine today.

And I look after my shit so they don't get scratched, damaged or subjected to extremes.

Steam has removed games.
PSN has gone offline for extremely extended periods of time and will likely get shut off for the PS3 at some point.

Xbox Live was depreciated on the Original Xbox, Microsoft will likely do the same with the Xbox 360 at some point.

Digital Stores don't last.

All my old console games work fine, it's the console itself that has issues, I.E. Failing optical laser in the PS1 or removed the clock capacitor in my OG Xbox.

Nothing lasts forever. Precedent is there for online distribution stores to be shut down... Even those owned by big companies like Games for Windows Live!