That's a definite no to MGS4. I doubt they can port that to the PS4 Pro. It's too tied to the PS3 architecture. They'd have to remake it from scratch like they did with Twin Snakes.
As for what I'd like.
I'd like that completed but never released Wii Rogue Squadron collection to come to Switch. I don't even need the resolution to be upgraded.
The Portal series and Left For Dead would be great on the go. Portal might be able to make good use of gyro controls.
Maybe MGS5 or the hd collection. Just port the PS360 version of MGS5 and there'd be no problem.
Oddly enough, many of my most wanted games are in fact coming, RE4, the Final Fantasy series, Assassin's Creed rumors look legit, ect.