I am personally disappointed and hope that rumor is incorrect. I was looking at a Switch Pro in terms of developer complexity, and what the easiest way to get to a more modern 4K system would be. With last-gen, both PS4 Pro and Xbox One X added one additional tier: you had base PS4, then PS4 Pro. Pretty easy. With Switch, every game already has to target two tiers: docked and undocked.
With a Switch Pro, literally ANY type of update to the main SoC, in both CPU and GPU power, should easily be able to hit the current Switch's docked performance while in handheld mode, with maintaining (probably extending even) the battery life. So with that being true, it would mean that Switch Pro portable mode would be the same developer-target as current Switch docked mode. Or another way of putting it: if a game on Switch right now targets 1080p in docked mode, it would simply run in that same 1080p mode while portable on Switch Pro.
The Switch Pro would then add one more, actually new third tier for games to run in: docked, 4K output. I do believe this would be 4K DLSS of course, but other perks could come into play as well (higher resolution textures, etc.) while using it. NVIDIA's DLSS is amazing in games that support it, and that is precisely why it would work so well here: being part of the Switch Pro's main spec means of course that every game can utilize it to its full potential, and probably provide even better results than what we have seen on PC just due to console's more close-to-the-metal and fixed development platform.
But considering that current docked versions of games are more often than not sub 1080p for bigger games, and some more demanding games are dynamic with 720p being the ceiling...would aiming for current docked performance really be worth pushing sub 1080p resolutions on a 1080p screen?
I totally get what you are saying, like I said, I was thinking about Nintendo doing it in as simple a way as possible for developers. If you have a Switch Pro, it just runs all current Switch games docked modes as its portable mode. No need for any additional developer input. For unpatched Switch games, Switch Pro would run it the same while docked then as well. But then newer/patched Switch games could run in 4K DLSS in Pro docked mode.
That way, buying a Switch Pro would get you a upgraded experience no matter what: for people who play portable mostly, suddenly they are getting the graphics/resolution/performance that docked mode people were getting before. And primarily docked mode people (like me) can have a much nicer 4K experience.