Right now Jaylen and Jayson are scorers. Even in college they weren't really passers. They're not going to all of a sudden turn into versions of Gordon Hayward. Comparing their current years to Hayward, LeBum and Kobe (since someone mentioned Kobe)'s 4th year in the league those you can see that Gordon and LeBum have much more of a playmaker's instinct, with 20%+ assist %age. As for Kobe, he had Shaq to pass the ball to.
BUT...what I think the OP is referring to, and what I think the next evolution for the Jays is, is to be able to be much better at driving and kicking. That's really where a lot of Hayward, and LeBum's, assists come from, from driving, attracting attention or drawing a double, and then kicking to an open player. Both Jays are more than capable of doing that. The challenge is knowing when to do it, where the opening will be, and to then deliver the pass correctly once they draw the defense.
Right now both Jays are still primarily score-first players. But I think they can get there. This isn't NBA2k where you can just dial up their assist attribute...it's just real game experiences where they will/should eventually figure it out. If they don't then yes they will be ultimately limited. But they've got time and the right coach to figure it out.