A dataminer has found a reference to 240 Hz support in the latest version of the Switch engine. Whether the Switch will be technically capable of this is questionable. However, this compatibility could give the Switch successor a 40FPS/120 Hz mode.https://www.notebookcheck.net/Nintendo-Switch-2-engine-to-support-240-Hz-according-to-new-leak-and-could-offer-40-FPS-120-Hz-mode.834073.0.html
You can't be serious if you believe the switch will put out 240fps in anything other than the main menu, at which point it might as well run at 60.
Perhaps Nintendo are making such changes because even though the switch 2 won't be able to, maybe they're already thinking about a switch 3 or 4 and how it'll be able to boost fps that high in older backward compatible games?
Idk seems more forward thinking on their part.