The Rockets are not in a bad position if they make the right moves. Harden is 31 and wants to win now. Move Harden while he still has high value at the end of his prime and get great assets for their rebuild now. If they can get Simmons and more, make the deal. Move Westbrook for shooters (or expiring deals if they can't get shooting). Fill out the rest of the roster in free agency with more shooting.
Simmons is a young star who is locked in for 5 years. Great piece for a rebuilding team. Surround him with maximum spacing and he will have his best year. They can add another star in later years when they get cap space.