I think bottom line is Hendo means alot more to SF then he does to the UFC.
He brings SF a high level guy who can challenge their top guys at 185 and 205. Gegard needed a wortwhile challenger in the worst way. And Shields has been talking about his desire to fight truly top level guys. Hend fits that bill.
Conversely, Silva has no interest in a rematch, and 205 is stocked in the UFC.
However there is a risk involved for both orgs.
If Hendo sweeps 185 and 205(and god forbid beats Fedor) then Dana has all the ammo he needs to mock the SF talent.
But he could also start a a movement away from the UFC, he gets away from Dana, which Im sure alot of fighters want to do, he gets great exposure on CBS, which Im sure alot of fighters would enjoy, and he gets the freedom to work his business dealings as he see fits which im sure any person, let alone fighters would want. So he may not mean much to the ufc, but him leaving could cost the UFC in a big way.