Detroit could be looking to move Josh Smith/almost certainly is looking to do so in order to clear cap space. My guess is that Van Gundy would prefer Monroe to Smith, though I could be wrong.
Sixers absorb Smith's salary, Pistons free up cap room to sign Monroe and get a better suited player for their system in Thad.
Sixers will still suck next year and land in top 7 of lottery, because Smith does nothing to move the needle. I anticipate that in general the 76ers will look to be more aggressive in offering their cap space as a harbor for other team's bad contracts. Thad for a bad contract and a future draft pick is almost certain to be a trade that takes place this offseason in my opinion. Smith for Thad is just one potential scenario.