Trade challenges are the worst :)
NETS:
They wouldn't ever trade Durant unless something catastrophic happened. However, this is easily the best return they can get for a rebuild.
WARRIORS:
They do this to retool. Curry is a ball hog and Dray is too old to keep playing. They get Brown and some nice young players who can keep them in contention. Losing Curry hurts, but could be necessary. All they have to do is admit they need help and fix their problems.
CELTICS:
This would be epic. Reuniting Steph, and Durant would be a legendary story. A championship would be the cherry on top of the multi layered cake. This would be a ton of fun and super interesting. Getting Draymons keeps the defense together. The trade would leave them limiting in depth. However, with a core of Curry, Durant, and Green, depth is just a number.
ROCKETS:
The Rockets do this to build around Jalen Green. Claxton can start alongside Wood and Pritchard can be Green's running mate. They would be a great team in the future. The picks can help them rebuild further.
(P.S. none of these teams would ever accept)