I doubt Dana would have much to do with it if Francis wanted to come back. Dana doesn't run TKO. There's bigger fish than him. If Francis wanted to come back and they thought he would be worth it, they'd make it happen.
But Francis might not even want to come back. He just had two huge boxing paydays that the UFC will never match for him. He got KOd in his last boxing fight and his last MMA fight for PFL no one really cared about. The UFC could very well just offer him less than what they were paying him before.
Also, dude is like 38. He doesn't have that many fights left in him most likely. The UFC aren't shelling out huge cash for that.
They know that Francis doesn't really have many options either if he wants to continue fighting MMA. He can come back to the UFC on their terms and fight a couple of times for what they want to pay him, or he can go off and fight in some other org. No other org is going to offer him anything near what he wants, or what the UFC would lowball him with.