From what I have read Fedor's contract is worded so M1 has to offer the UFC heavyweight champ 1 million dollars on top of what the UFC is paying them. Fedor stated that it is up to the UFC and Randy and the fight will happen. He also, said that his signing with M1 won't affect his legacy because M1 wants to work with other organizations to make the big fights. So, it is possible for him to fight anyone in any organization. I think the other orgs will work together but the UFC will not.
I don't think the Randy fight will happen until late next year due to legalities involved, but in the mean time if he fights Barnett, then goes on to fight Randy and win, I think we can close the book on who is the greatest HW of all time.