Kawhi is certainly the better player currently, there's no debating that.
But Kawhi would have to really churn out some big stats these next few years while he's still in his prime, win a title or two more (preferably beating the Lakers in the playoffs in the process), and not have to miss a bunch of games each year. LeBron has such a big lead on Kawhi in terms of career accomplishments it will be a monstrous task to pass him.
Kawhi could make it a more interesting debate, I suppose, that seems possible. Passing him seems rather unlikely.