According to Dana White during the UFC 122 Fan Q & A: (via Fighters Only)
"There won’t be an immediate rematch (between Brock Lesnar and Cain Velasquez), there is no need for one. After the fight Brock took some time off to go hunting; he and I haven’t spoken since the fight so I’m not sure what he wants to do next."
"He never asked for Roy Nelson, that’s not true. The last thing I did hear was that he wants to fight Frank Mir again. That fight kind of makes sense so… We will probably see Lesnar fight Mir next, I think that the rubber match makes sense."
"Eventually we will do 125lbs. I believe we will open it up a lot sooner than people think we will. There are going to be more title fights in more places."