Yeah it won’t happen, but probably because Brooklyn have no tradeable / valuable comparative assets for Harden rather than for the reasons you detail. It’s a different situation from the thunder set up in that 1) these are players at a very different stage in their careers 2) Irving can actually shoot the ball, and will pass to teammates he trusts 3) they won’t be playing Houston small ball so would also have a strong presence in the key both defensively and offensively 4) In KD and Harden they have two players who basically always require a double team, stock up on a couple of 3 and Ds, and that’s open buckets every where else on the perimeter.
Personally I’d like to see it and it might be the only thing stopping Lebron from another bully run.