I believe in the Super Metroid remake. I also believe it's by Mercury Steam.
As others pointed out - and as with pretty much any other Metroid title I've played - I believe conserving or improving the atmosphere would be the main... concern? of the remake. 3D* seems like the way to go, to add more depth to the game. Although, if it's Samus Returns-like in HD(Regarding amount of detail and overall richness) I think at first that'd be underwhelming but that was also a 3DS title, which actually makes it impressive for the system, plus they should be developing this remake by adapting it to Switch's capabilities this instance. Mercury Steam games got really nice artistic direction, so there should be confidence on that regard.
As for the gameplay changes, I have no clue on what they could add other than the free aiming found in Samus Returns(Didn't play it yet), Also, 30FPS or 60FPS? Samus Returns was 30FPS while every other 2D Metroid was 60FPS. Both choices, right? Oh, one can hope. Did you Metroid players notice a worse reaction time when playing and platforming on Samus Returns compared to older Metroid titles?
To be fair, this is all a bunch of
ifs aaaaaand I probably shouldn't even be discussing about it because I have played three 2D Metroid games(ZM, SM and Pinball ayy) and I first played SM a couple of years ago. Fusion is my next one!
Edit: *3D as in polygonal like Samus Returns, not 3D a la Prime LOL
I can't imagine this relationship being a one-way street. What does Nintendo have to give to Microsoft?
Other than MS getting more income, I believe it's likely they are working on some sort of collab to put their(Xbox) xCloud on the Switch. That seems to me like a fair chance for Xbox on growing their brand recognition over in Japan, even if through/related to Nintendo.