Brown + kemba for harden + covington/gordon actually makes sense for both teams.
Neither side would be totally happy, but that is the sign of a fair trade.
C's get the league-favored superstar they need, and open up wing minutes for Hayward.
Rockets get a very high upside emerging star in brown, and a solid star in kemba. They could become a surprising team, especially if they keep Westbrook.
Not sure I'd do it. Briwn and Kemba are good Celtics. But a Tatum/Harden/Hayward triad does have potential.