Harden, now that would be fun. Going along with the slim chance that there is a chance, I would trade IT (all star), the 2 BKN picks (likely lottery for both), Turner, and Amir. That just might get it done. We may have to take something else back to make roster slots work.
I put in IT because I think long term, keeping Smart and Crowder is better as they seem to me to fit better with Harden. I would not have a problem including Sullinger but he may not have that much value to Houston.