He's averaging 6 assists in his career; he averaged 6 last year splitting play-making duties with Ellis (who also averaged 6 at GS last season) - he's got the keys now, so his usage and APG should go up. I'd say he's looking at around 8, give or take. In order for him to be elite, he doesn't need to be elite in all those categories, it's how he balances them all out and incorporates them into the offense. He's already got great passing, vision and ball-handling ability. He's one of, if not the best PG at spreading the floor; great in swing-ball situations/curling-out. He doesn't need to be effective with the ball in his hands all the time and has a great-understanding of where shooters need to be positioned on the floor due to actual-experience. He's arguably the best shooter at his position (+ the league) - which opens up EVERYTHING, the offense will have x-less % of being stagnant and losing its momentum/fluidness; defenses won't have the luxury of over-compensating on P&R/hedges/outlets/RTTR/cut situations etc etc. He basically breaks the 4on5/help-defender schemes that defenses implement on teams that have incompetent shooter(s) at the 1.
With usage-limitations and injuries, he hasn't developed the awareness and consistency to work and break-down half-court defense-situations, to where needs to be at an elite level - this season (if he stays healthy) I can see him getting over that hill.
I hope so. I want him to keep improving. It'll only make the team better.