The problem with people who bank on their own team's young guys greatly improving is that the league is full of teams with young guys. But we don't see all these teams necessarily becoming fundamentally better, even as their young guys get better. The main reason is that for all their improvements, most players still don't become that great.
Having a bunch of players become a better type of mediocre doesn't do much for you. They still aren't good enough to consistently win. Especially when the young guys just end up taking minutes from older guys as the young guys improve, and we often end up with a less effective team, but with higher hopes for the future. For example, if Young ends up taking minutes from Turner, we might view this as a good turn of events for the future, but it won't really help the team now.
We can expect that the rookies will mostly hurt the team as they get minutes for the sake of development and not based on their actual contribution. We could see Rozier get minutes now with the goal of making him a decent contributor by season's end.
We have these guys playing 1-3: Smart, IT, Rozier, AB, Young, Hunter, Crowder, ET. As the newer guys improve, it only really matters if they become better than the guys they will be taking minutes from. If Hunter is surprisingly effective, it likely means he is still less effective than ET and AB, making his contribution mean little as far as team record is concerned. This is also why it seems to some that we have a logjam in the backcourt despite no one apart from IT being above average at their position.
The best way to get value from a bunch of these guys improving is to package them in a trade to get a single player who is better than all those guys (excluding IT, who is a heck of a scorer).
That being said, it is still quite possible that Smart shows major improvements in his ability to get to the rim.