I want Daft Punk to return, but if they wont or cant then Id be happy with M83 doing the score. Oblivion's score is a different "speed" and style than Tron Legacy's score, but its absolutely gorgeous imo and Im sure theyd make an equally gorgeous Tron 3 score.
One area that Kosinsky really needs to work on is the action sequences. To quote George Lucas "faster and more intense". Thats what Tron 3's action scenese need to be. Better choeography and use of the discs wouldnt hurt either. In the arena boxes it was pretty good, but the fight in the night club was pretty ho hum. It wasnt terrible, but it lacked a certain amount of "Oh ****! Did you see what he just did?!"
The visuals and score were perfect. Those are two areas that so far Kosinsky excels at. Seriously, oblivion and Tron Legacy are two of the best looking and best designed films out there Imo. So at the very least Tron 3 should be beautiful.