I don't feel Smart will ever "take over" he most likely will never have the offensive out put to satisfy some. He will be a team leader, a lock down defender, and a guy every team should have on their roster, while scoring good enough to justify his minutes. I'm thinking 13-15 points, 5-6 rebounds, 7-8 assists, with some killer D, and a take no prisoners attitude that others imitate.
It's like asking, when will Draymond Green take over on the Warriors? He gives you things that don't show up in the stat line, that get you important grind it out wins, wins you had no business winning. Everyone thinks Curry is the reason the Warriors are so great, it's not, It's players like Green. Labron wishes he had a Draymond Green on the Cavs roster. Smart will grow into that guy. He's the guy that puts you over the hump.
If that's not good enough for you, keep "yelling" for him to be traded, and someday you'll say "our team has no passion, they just go through the motions."