Well the alternative for some games is going to be 0% of Switch owners can play a game, if its too hard to port to the current Switch. Some % is always going to be better than 0%. 

There is also that supplemental compute device they patented, when you using chips this small, who knows maybe they could make something like a companion device for the older Switch models that has the new Tegra inside of it and can handle the graphics processing. 

I think Switch eventually is going to become more like Steam than a piece of hardware, an ever growing software library, as you scale up you get access to more and more games and your old games come up with you rather than something that is completed anchored and stuck to one hardware spec/hardware model for 5-6 years. 

We'll see. The leak in the Switch OS from hackers mentioned a Tegra 'Mariko' with custom model number that isn't the Tegra X2. 

X2 is actually a fairly old chip at Nvidia, they likely can give Nintendo something beyond that by 2019/2020. 

I'm not sure if Nintendo necessarily will mandate anything either, as far I know they didn't mandate for example that Minecraft had to work on all 3DS models (it only runs on New 3DS). It will be up to the developer I think. 

Couple dollars when we talking about 16GB carts, but with 32GB carts its even bigger difference and thats why no one using 32GB carts, but and even couple dollars per game is clearly less profit for devs when you multiply that with number of sold games.

I admit, I am one of people that were saying that price point difference of carts is not problem that really can effect on 3rd party support in some way, but when you have several very trusted 3rd party insiders with great track record saying otherwise and when you have like fact that no one using 32GB carts on Switch even if they area available from launch, I now think that's definitely problem that affecting on some 3rd partys.

Both those rumours didn't come from any trusted source or source with good track record. People who saying this things about carts are not Metal Dave (he claimed that NX will use AMD and it will be at least strong like PS4), but people from Resetera that are very trusted, Vern, Benji and Nate Drake.

If you are intresting what those guys exactly said about carts problems you can read here, going from page 5. 

https://www.resetera.com/threads/are-carts-hindering-switch-reach-in-the-same-way-it-did-with-n64.36840/page-5

People claiming the exaggerated performance for NX and Sony paying MHW to be kept out of Switch also claimed the insiders were trustworthy and had plenty of leaks provided and true. Anyway I'm not saying your claim is impossible (even though I think it is hard to say they couldn't or wouldn't release digital only or part download).

If I'm not wrong one had quoted ZhugeX about the cart price being quite similar to the royalties for BD on Sony/MS.

And anyway, 5-10 USD more for the cartrdige compared to the BD isn't a dealbreaker and as others said Nintendo could eat up part of the cost be it through marketing the game, giving better margin for the 3rd party, etc and not necessarily this would be revealed and even if revealed that doesn't make it standard that everyone will ask. Or do all companies require their game enter PS+ or GwG, marketing, space on E3, etc?

People, but no one from trusted sources said those things, espacily not people that I mentioned.

ZhugeX actualy said that you need less than 8GB card in order to have same profit margin like on BD for XB1/PS4. So with 8GB and espacily 16GB cart they have higher profit margin, not to mention 32GB carts cost that no one using because they are still too expensive. This post down sume up things more clearly

https://www.resetera.com/threads/are-carts-hindering-switch-reach-in-the-same-way-it-did-with-n64.36840/page-9#post-14045228

$5-10 more costs is definitely deal breaker because when we talk for instance only about 100k copies of sold game, we talking about $500k-$1m less of clear profit for 3rd party, for 500k sold games we talking about $2.5m-$5m of clear profit, for 1m sold copies $5-10m less of clear profit.. Nintendo would hardly take costs on itself or take smaller margin of profit, if they do that once than they would have same request from other 3rd party publishers.

That's also reason why some same games have higher price than on PS4/XB1, but problem is when we talking about $60 price point that game would have in any case, and you can't really gave price point of $70.

Sure 5 USD per cart when selling 1M copies is 5M less profit. Now how much profit you make selling 0? Because I'm pretty certain GTA V would make more profit by releasing it.

$5 x 10 million copies -=  $50 million dollars. Can't afford to lose that profit margin.

https://www.tweaktown.com/news/58516/gta-online-earned-1-09-billion-analyst-firm/index.html

What's that? GTA Online has made over $1.1 Billion as of 2017 on 80 million copies (at the time) of the game? That's nearly $14 per copy sold. I can't imagine how Rockstar could make up that $5 per copy in revenue. They'd definitely rather shelve a complete or near-complete copy of GTA V for Switch than eat a $5 hit on the profit margin on the front end. It'd be way more profitable to wait years for the cost to cartridge to decrease rather than try to make that up in GTA Online.

Makes sense.

Sure 5 USD per cart when selling 1M copies is 5M less profit. Now how much profit you make selling 0? Because I'm pretty certain GTA V would make more profit by releasing it.

If we talking about 32GB carts, we probably talking around $10 price difference instead of $5, so on 1m sold games we talking around $10m less profit. Profit matters in any case, it would main reason why they would released game on first place on Switch and they would go for highest profit. Saying that, maybe game is coming to Switch in any case but they are waiting or Nintendo promised them cheaper prices of 32GB carts next year, or something similar, only time will tell.