So hypothetically, they trade the 1 to the Kings for Cousins and then package Russell and Randle for Westbrook and then sign Durant in free agency. Fill in the rest of the roster with role players and veterans.
Hypothetically, sure. But I don't think the Thunder are trading Westbrook for Russell and Randle outside of a hypothesis. If they want to trade Westbrook, I think they could find a better offer.
Obviously if KD returns, RW is staying put, but if KD leaves, I do think the Thunder will be looking at a reboot and selling off assets since RW is a free agent next summer. Given, I think they go into full bore rebuilding, I actually think Randle and Russell for Westbrook isn't a bad return, depending of course on what they think of them. I mean Russell was the most recent #2 pick and played fairly well down the stretch on a terrible team. Randle was basically a rookie and showed flashes of why he was a top 7 pick. I think other pieces/future assets will be in play (but the meat will be Russell and Randle), but remember RW is a pending free agent with no guarantee he re-signs which hurts his value some (it is also why I think the Kings end up trading Cousins this summer).
Again no way the Thunder move RW unless they lose KD, then I think all bets are off and I would actually be surprised if the Thunder don't move RW. The Lakers of course would be competing with Philly (they would only do that if they made other moves to improve the team), Boston, the Clippers (you know a Russ for Griffin type trade where Russ ends up at SG next to Paul), and maybe one or two others (the Knicks if they go into win now mode - trade centered on Porzingis, the Wolves theoretically have the assets even outside of Wiggins and KAT - though it might take Wiggins, etc.). Not sure many other teams will be in play given the cost it will take to acquire RW and given he only has 1 year left so the team still needs to be good enough to encourage RW to stay.