Switch will undoubtedly receive long tail support for quite some time, which will probably mostly manifest mostly as cross-gen games since there's no reason for it not to, but jumping from there to all the games being cross-gen is quite a leap, especially when it comes to certain types of evergreen titles like Mario Kart.It's not as if there isn't a precedent for that. Sony took a very similar stance, only to follow it up with a very prolonged period of cross-generation support for their biggest games.
Granted, Sony is also in a perpetual competition with Microsoft to shoot themselves in the foot as many times as they possibly can. And while Microsoft might have had the upper hand in that competition for the better part of the past 20 years, Sony is certainly trying their best. I doubt Nintendo has much intention of joining that particular competition.
That will be probably be somewhat true in the abstract, but for many of them, including a Switch 1 version would substantially change how the games are concretely being built.Frankly put, it's extremely unlikely that if the hardware is so iterative as people are asking for, that the newer games would have any "new experiences" that couldn't feasibly be scaled down. We're so far beyond the age where the power differences alone enable easy meaningful differences to the types of games Nintendo make that you'd see in the early years of a consoles life, that they wouldn't be hurt by being cross gen.
Something like TOTK couldn't have been cross gen because no doubt it's already pushing the Switch hardware, but there's also zero chance you get anything like TOTK in the first years of nay console because it's the kind of game that would require years of work knowing exactly what the hardware is capable of and designing around it.
I don't think Mario kart will be cross gen, but I also would put money down on that 100% being a business decision and not one driven by technical limits at all.
Also if anyone can figure out how to integrate ray tracing into gameplay, it's Nintendo.