The Sixers recent draft history has been stellar in my opinion, with Thad Young picked at 12 and Mareese Speights at 16 the following year. If we can get another player like those two out of this draft, it would help the team immensely. Since their pick this season is 17 if the draft is as good as last seasons, we could get lucky again (or at that point would it be considered skill/)
I'm not thrilled with the idea of another big man project. Unless we can trade Dalembert, which I think the team is trying to do, we should have enough big men with him, Smith and Speights. Under most circumstances only one of them is going to play anyway; with Brand, Young and Iguodala getting a lot of PT.
Whether we keep Miller or not, we're going to need to replace him and his production eventually. I figure he has two-three good seasons left with the right team, and is probably too defensively limited to be the starting guard on a Championship team. (Although I would say he was better than Derrik Fisher) That doesn't mean we have to replace him this season.
It would be best if we could sign him to a reasonable contract and buy us a few seasons to find a better player, I'm not sure how much other teams will want him. The other option would be to let him go and pick up another free agent guard, or find a player in the draft or free agency.
In a motion offense, the team relies on everyone passing and moving without the ball. That puts less emphasis on the passing ability of the point guard, who's primary role is to bring up the ball, meaning he needs to be sure-handed. It would also help if the player had a good outside shot. Theoretically, this implies that we don't need Miller, but a player who can defend, bring up the ball and hit the outside shot.
This past season we really needed his scoring, but with Brand in the line-up and Young only getting better and Iguodala improving as well, I don't think we'll need as much scoring from the point, just enough to keep the defenses honest and spread the floor. Miller is an inside scorer, but I'm not thrilled with relying on that when we have better post options.