I agree that it seems likely for Pokemon Home or Sleep. I don't know if I trust them to properly handle a remake of Diamond and Pearl after their mindset for SwSh. With that attitude, they'd approach it like, "Well, I guess we're obligated to do this, so let's get this over and done with or whatever." And just do the bare minimum within a year, because their release schedules don't allow room to breathe.
It could potentially be neat, if and when it happens, though. Just imagine...
Expectations on the Switch, an HD console: Giratina, a terrifying, dark chaos creature from another dimension, tears through time and space to appear before you!! Imagine some combination of the original appearance in Platinum and the alternate art of Garchomp & Giratina GX.
GameFreak/The Pokemon Company: Aroo!!
Giratina blinks into existence in front of you and floats there.
Expectations: Oh....
Sarcastic speculation of a dark future aside, I am curious. I'll be sure to check here on Thursday.