I doubt this scenario is realistic, but I would love to see Kemba traded for a big and the Celtics running Hayward as a full-time PG LeBron style. I think Hayward's game will age better on both sides of the ball, and he'd hopefully put less wear-and-tear on his body by not banging with bigs down low all season.
Hayward/Brown/Tatum/big/big
or
Hayward/Smart/Brown/Tatum/big
is a pretty large lineup with a lot of competent ball handlers .