How about IT4 + Crowder + Smart for Kyrie?

Boston: Gains a superstar sitting, age-wise, right in between Hayward and Jaylen/Jayson, as opposed to one who is older than Hayward, which gives them more time to wait GSW out, and they move Crowder and Smart out of the way for Jaylen, Jayson, Yabusele and Rozier to develop. Of course they lose out in the short run, but I can´t see Boston fans going mad about losing a chance to get swept by GSW, at best.

Cleveland: They lose just a little D with IT4, and they get so much better on the 2 and 3. I´m not sure you can play Smart as a starter on a good team, since he can´t shoot, but you can use him exactly like Boston does, to shake things up when needed. Smart and Crowder have terrorised Klay and Curry before, repeatedly, and they will do so again. Also, with Crowder, Cleveland gets a wing who can cover KD and catch-and-shoot 3s, which is exactly what they need to move Bron up to PF and TT to C, their best positioning. That, in turn, allows them to trade K-Love for either 2–3 solid starters/rotation guys, or, possibly, a star(ish) 2-guard. Maybe the Hornets would bite for a straight up K-Love-Kemba trade?