First off, when the Boogie Cousins for Buddy Hield trade went down, AD mocked Sacramento by saying he would never have come here to join Boogie. So forget about the notion of AD signing an extension here.
Secondly, as great as AD is, I'm not sold on him as a clutch player when the chips are down. Sure, he'd be an elite complimentary piece to an already established alpha such Kyrie or KD or LBJ. But as the lead dog himself, no thanks. He's not that type of player.
He piles up stats and often dominates, but has also been pushed around during the playoffs. Where he lost me was when he allowed Draymont Green to be able to guard him 1o1 by consistently opting to take fade away jumpers rather that work his @$$ off to punish him down in the post. He just can't or won't do that -- even to a smaller player (yes, I'm aware Draymond is a great defender). For that reason, I'd never be on board with acquiring him unless it was to pair him up with a true alpha.