I was talking about this the other day in the PC thread and had a wild idea. I'll post that here:
One thing I will say is after seeing the Steam Deck, it will be interesting to see if Nintendo goes AMD and x86 instead of going Nvidia and Arm at some point in the future.
For some reason I don't think it is likely. When I try to justify my impulse, I think that while Nintendo has gotten overwhelmingly better in the Switch generation when it comes to considering ease of development for third parties, they think much more in terms of power-efficiency when they develop the hardware of their platforms, at least that has been their philosophy since the Wii. ARM is just much more power efficient than x86 at the 7-20w range, which Switch's successor will likely target. Just look at what the arm-based Apple M1/M1x/M2 is (will be) doing in that range. While AMD's low power options keep up near the top of that power range, they need to be cooled much more since they need to stay at that top of the range more often.
Many of Nintendo's less talented first/second party developers (like Game Freak) are also more comfortable with ARM, they've been using it since the Gameboy Advance era, and struggle with change.
Furthermore, the distance in game support is going to decrease between x86 and ARM in the future than it was in 2017 and is today. Steam just released native ARM support in September. Developers are also quite use to ARM as an architecture, which wasn't quite true of the PowerPC processors that were present in the consoles before the switch to x86/ARM. It isn't as hard to port to ARM as it was in those prior generations because almost every engine supports it today, while engines often had to be proprietary then and therefore ported before porting the game.
I think Nintendo is going to stay with ARM unless their next platform goes into the 25-40w range when docked due to a heftier cooling system in the dock. If that is the case, then they might go with AMD because AMD is quite competitive in that wattage range.