First, I can say with 100% certainty that there are current negotiations for Randy Couture to return in November to main event, and that the current proposed opponent is Brock Lesnar. They can't get Fedor, too many issues to work out on short notice, and he has a US-only non compete with Affliction.
This will be a new contract, not a return to the old one. It will likely pay him more and give him more benefits, but it will lock him into the UFC for the long term. In exchange for signing it Zuffa would drop all breach of contract charges.