I think the sky is the ceiling for him honestly. Jason Kidd was not a high scorer ever, but he was a super star. The reason he was a super star was not because he was super fast or scored 28 a night, but because he was super intelligent, same as Smart. Smart dominates games sometimes just on defense.
He causes offensive players to travel, to run out the shot clock, to charge and push him, to throw the ball away, and most times, he completely takes an important player out of the offense by denying him the ball.
The way he plays the pick and roll will be iconic, and players and coaches around the league will copy this technique in the future. His teammates already does some of the same techniques.
I believe he can guard LeBron with ease. Maybe not this year because the refs won't allow it. But Smart's a "Smart" player, no pun intended, and knows how to follow a defender without fouling him, and how to use his left hand to shield the eyes of shooting defenders. He also has an incredible wingspan that allows him to block shots, and reach for balls without touching players.
Offensively, again, he's a Smart player. He's always giving the ball to the right guy, but the shots don't necessarily fall. He does need to drive more, but he's not playing point guard much, and he doesn't get the ball as much as he should. He is a rookie, I even forget sometimes.
What I have seen from him in the past is that the guy simply dominates the game without scoring a ton. This is the first time in his life that he's worked on his offensive shooting. How he's been a winner years back was his teammates believing in him, and coaches allowing him to roam a little bit on offense.
Allow him to post up and go after rebounds, instead of the safe play of guarding the back court in case of a leak out/cherry picker. When he roams on offense, more times than not, he's cleaning up shots under the basket, getting crucial rebounds in traffic, due to his good straight up vertical along with his reach.
What I would like to see in the future is him improving his 3-point shot and his mid-range shot. He should develop a floater. I don't get why more players don't do this all the time, it's pretty unstoppable. Just think Kareem Abdul Jabar, or how ever you spell it. All he did was the hook shot and it worked. Develop a floater, and finish at the rim. I see him going to the foul line a lot in the future as well, because of how physical he is.
IMO, and sorry this is so long, he's already developed a reputation as a shut down defender with the refs. He's not been in foul trouble much for a physical defending rookie. Anyways, carry on guys, we need to get a victory, no moral victories.