The latest rumours come from a recent
Nate the Hate podcast in which the host claims to have been told that the Gamescom tech demo saw BOTW running at 4K 60fps, with the emphasis of the show being that "load times had been erased". Again, this is not to suggest that the Switch launch title will be re-released with the next hardware, only that it was being used to demonstrate to showcase the successor's technical improvements.
There are also claims that the demo was utilising DLSS 3.5 — Nvidia's real-time AI upscaling technology — though it may "not have been utilising the full feature set" of the 3.5 version, e.g. frame generation. This is something that has been
suggested for a Switch successor for a good few years now, though seeing the beefier 3.5 version thrown around sure is an interesting prospect.
Later in the conversation, the host stated that a March 2024 date came out of a lot of the conversations he was having, though he couldn't say whether this was a reveal or a release date. Rumours from earlier this year stated that the Switch 2 would be
targeting a release in late 2024, remember.