I see Switch 2 (docked) being able to nail all games at 1080p 60 FPS. 1440p 30 FPS or 1440p 60 FPS could be possible, but way less common. 4K is almost completely out of the question, unless Nintendo has a really efficient chip set. Or they're willing to have a very expensive product. I do think apps like YouTube, Hulu, and anything else like that will support streaming in 4K in docked mode. And I think the tablet screen will be 1080p.
Speaking of resolution, Sony and Microsoft brag that 8K resolution is supported for their upcoming consoles. But let's be real, virtually nothing will use it or be able to run it. They'd be lucky to have streaming services supporting 8K in 3-5 years.
Well with DLSS apparently this new model will already have 4k. Maybe like 5% of people will care about a difference between DLSS 4k and native 4k. So if upgraded Switch has 4k then obviously a vastly more powerful Switch 2 will have 4k. I expect Switch 2 games built for the system will run 4k, and then ports of PS5/XBSeries games will run at like 1080p on Switch 2, using that drop from 4k/90fps or whatever absurd thing those other systems target down to a perfectly fine 1080p/30fps in order to be able to do ports better than Switch can without all the work to downgrade them. 4k (using DLSS) should be the standard for games built specifically for Switch 2.