Considering Remake was a game originally made for PS4s it isn't as all surprising it is able to run well on a Switch 2. I'm sure some improvements were made to presentation for the Intergrade release on PS5, but its still mostly a PS4 game on the base. Now Rebirth on the other hand, that's a game I'm really interested to see get going on Switch 2. The game already had some performance issues and ran at a really low res on PS5, so shrinking it down further will be quite the challenge.
And that's another thing....
When the Switch 2 store eventually gets the plug pulled, and you know it will, unless you have a backup of your games or have lost the key cards, well, I guess you're just Shit out of luck. Oh, I'm sure Nintendo will gladly resell it to you at full price again, no doubt. This basically is killing the resell market too. I assume once the key card is used, that's it's locked to that account with no way to get the game on another system, even if you remove it from your account.
No, game key cards don't lock anything to a specific account. Basically the cart has no data aside from giving the digital store permission to start a download for the game it is for. Even after the download, you still need the cart inserted into your system to play the game. It is similar to how you still need your disc to be in the system on PS4/PS5 or Xbox One/Series despite the game getting installed to your hard drive.
You can resell it or lend it to a friend just fine and I'm sure the Switch 3 will be just as backwards compatible as the Switch 2 is. Pretty much every console that releases from here on out needs to be endlessly backwards compatible. To make sure its clear, the key card could be used on 100 switch 2s and all of them would be able to download the game. Only the system with the cart inserted would be able to play the game though.
Game key cards suck ass, but for Nintendo's cartridge based media it was unfortunately inevitable that their physical releases would start to suck. They're in the 4k era now and we've reached a point where games like Red Dead Redemption 2 or Cyberpunk 2077 are so big they don't even fit on a single blu-ray. Inevitably Nintendo wouldn't be able to manufacture cartridges for 100+gb games without them costing absurd amounts. Then we'd be right back in the SNES era where some games randomly cost triple digits physically.
Companies have clearly been trying to push an all-digital future on us for the past 12 years now and this is just another big step forward for that agenda. Truly depressing, but inevitable with how these companies wanna run their business. My best advice is to do the sensible thing and just put CFW on your system and just rely on backups the moment the successor to your system comes out. Switch 2 releases? CFW on Switch time. PS5 releases? Time to pay close attention to the PS4 CFW scene. It doesn't replace being able to resell games if you're someone that frequently trades stuff in, but it's the best we got and for the most part it just demands a little more patience from you to get access to all the games you want.