I think he will struggle early on until he's accustomed to how things are in the NBA. Once he gets acclimated to the speed, power, refs, super stars all over the place, by mid season, he will go on a tear and he will be a point guard to be reckoned with.
As far as leadership, he's a natural born leader. Leading is his thing. But he will not push Rhondo out of the way, that's just not how he is. But the way he plays is "balls to the wall" and because of everything he does, people will just move out of his way and let him do his thing and lead. He's not selfish at all, but sometimes Stars (not saying he's a star) but stars have to stop being unselfish and take over. If a team doesn't need him to score, he'll be fine putting up 13 points, 8 asst, 3-5 steals, 5 rebs, 2 blocks per game, and shutting down the opposing teams guard/small forwards.