Count me as worried about this team.
We are reconstructing the failed roles from last year. Kemba will move the ball more, and play more like Isaiah did than how Kyrie played, but he's still going to take the same number of shots. Even Kantner, who is nowhere near the player Horford is, will nonetheless probably take about the same number of shots.
The franchise will only go as far as Brown and Tatum take them, and the priority should be to carve out the necessary roles for them before anything else.
I fully expect Kemba to be the adult Kyrie never was, and adapt his style some to the team's needs. I thought it would be possible to start Brown, Tatum and Hayward, but we would have needed a 3 and D point guard taking 10-12 shots for that to work. Smart might have worked out. With Kemba, we will need to spread the minutes of the three wings out over the entire game, or there will not be enough shots.
We won't have Rozier, and we better not get Morris back, but that isn't enough to sort out the starters roles.
We'll see if Stevens has learned enough from last year to make this work. I find it annoying that Ainge looks like he hasn't learned anything.