If/when they do a Switch revision it needs to be an upgrade across the board. The New3DS may have had a better CPU and much more RAM, but it had the same GPU as the regular 3DS and that prevented many games from benefiting from the otherwise better hardware other than better load times. And upgrade across the board would allow older games to run better and fix framerate issues.
A full-on Switch 2 in 2022-23 should use whatever the latest mobile chipset is then. The Tegra X1 will be almost a decade old by then. Nvidia would be the best choice as they get more per flop and it would help with backwards compatibility. But by then someone else might take the lead in that market. They shouldn't launch a new system until the technology is there to have a switch-like device capable of running PS5 games at least as well as the current Switch runs PS4 games.