An essential feature of BG games is the ability to acquire NPCs in your party and to control them directly. This immediately throws a purely real-time combat system out of the window.
I was never very fond of RTwP of BG1 and BG2, it was for me the only weakness of the game, not detrimental to playing but it was pretty much THE missing thing which prevented BG to be fully a D&D game.
Then, ToEE came out with its turn-based system and felt the most D&D computer game ever. Sadly, it didn't have the narrative depth and fantasy setting scope of BG, but it made me wish for a ultimate D&D game that had both features. If BG3 will be turn-based, it has a chance to be that game.