I've always seen Grass, Fire, and Water as the three most basic types followed by Electric, Normal, and Flying. If given the chance to start with anything different, it might only make the game easier, at least at the start. To change up the starter types would certainty be interesting, but I doubt GameFreak will ever break from that tradition in any future generation.
Sorry about that, I didnt think of that. I didn't remember that the starters already was revealed. Gomenasai community!