Nvidia has every incentive to make bc work on ampere.Just to toss it out there, Wii U achieved backwards compatibility by pretty much including a Wii within it. It runs pretty much perfect, down to even running GameCube games when modded because it's just a Wii, but it does drive production costs up. PS3 I believe did the same thing originally, which is part of the reason they gutted the feature when they needed to drive costs down. I know the general idea people run with is Nintendo achieving backwards compatibility via software, but honestly who's to say they won't go the Wii U or PS3 route again? And if that's the case suddenly it makes a whole lot of sense for Nintendo to offer a variant without Switch compatibility.
To be clear I'm not saying it's likely, this is definitely a rumor I need to hear reiterated by other sources before I put any stock into it. But I wouldn't completely dismiss it either, the idea really isn't that crazy if you think about it.
The big differentiator for the Switch, and those previous platform, is that Nvidia is providing hardware and software for Nintendo long term. In some ways it goes even deeper than Sony and MS AMD partnership, because AMD isn't creating the API and dev tools for Sony and MS.