That's not something AGDI will do. I also don't don't think it would actually be a good thing in general.
QfG5 wasn't really in a good place to start. The series had set up a lot of loose ends that need tying up, and there was a lot of power creep. That is, the hero already had already become so powerful, learned so much, and defeated such strong enemies that another game was going to become either a letdown or ridiculous. That means that, even if you started entirely from scratch and just wanted to make a fifth QfG game, you were already fighting an uphill battle.
There were parts of the game that actually worked quite well, and there were other parts that were disappointing. It would certainly be convenient if the latter of these could be directly correlated with the change in game engines, but that's not the case. A lot of the bad parts had nothing to do with the switch to 3D (and would thus still need to be solved somehow even after changing back to 2D), and a lot of the good parts were actually facilitated by that move (which means that those would be lost in the demake).
It would make more sense for them to make an entirely new game. So that's what they're doing