0% chance Nintendo is releasing a successor to Switch next year. The rumor is a more powerful revision using a more power efficient Tegra X1 (so no new architectural changes, no DLSS, no RT, etc.), launching along side Zelda. Nintendo is about to hit the peak year for Switch, why in the world would they be thinking of dropping it any time soon? I think its very feasible we don't even have a successor by 2023, a 2024 release is very feasible if Switch doesn't suddenly lose all its momentum next year. Furthermore, if a brand new system released next year, it probably wouldn't even be using the same architecture the upcoming RTX cards will be using, so it probably wouldn't be incredibly powerful, even with DLSS. It would offer no benefits to them to drop the Switch early, when its doing so well, it should be dropped later than usual, and it would only mean a rushed dev cycle for the upcoming system. Not practical reason to do that.
I don't want to see Prime 4 until its ready. Its already been cancelled once, and it was announced way too soon (Retro's build I mean) because of this, showing us a CG trailer "for the hype" (not quoting anyone specific) isn't going to make the game come any faster, they shouldn't show a thing until the project is starting to become a real game.