That's kinda the point. There's no remake going on there, as far as I can see it. The original map was already in 3D, all the guy is doing is making an engine to play the game from a first person perspective instead of bird's view.
Currently, all he wants to do is make an engine using GameMaker Studio for rendering the maps, no gameplay at all.
A remake of the original GTA is kinda pointless, anyway. Liberty City, San Andreas and Vice City were all done in more or less glorious 3D anyway, and the gameplay is virtually unchanged. So in a way, the game has already been remade.
A 3D variant of London 1969 would be cool, though, or the slightly futuristic city of GTA2.