Believe it or not, there is actually a TNA Impact Wrestling tie-in with Brock Lesnar. While UFC President Dana White has said publicly he wouldn't stand in the way of Lesnar returning to WWE, it's actually more complicated than that.
I'm told UFC officials believe Lesnar is finished fighting, however, they are hesitant to release him from his contract. The concern stems from the fact there will be "several" big money offers on the table for him if/when he becomes a free agent, some of which UFC wouldn't want to help facilitate by releasing him.
One interesting scenario is Bellator Fighting Championships (Bellator), which is now owned by Viacom (the parent company of Spike TV), is ready to make a big money offer to Lesnar if/when he becomes available.
One source close to the situation tells me under the condition of anonymity that Viacom officials would be interested in Lesnar making appearances on Impact Wrestling to put Bellator on the map while also raising the profile of TNA. Viacom has a vested interest in the success of TNA with Impact Wrestling being a valued-franchise on Spike TV.
There are already plans to use TNA programming to help promote the launch of Bellator fights airing on Spike TV in 2013.