I've been saying this for a while, but it Lesnar properly cross-trains and prepares the sky is the limit. As of right now it looks like he is. The guy is a freak of nature and is insanely strong. He would probably be hands down the strongest HWT around. He has great cardio and a strong wrestling background. He would fit right in, in the UFC due to the fact it is a pretty weak HWT divison and his strenght alone would be good enough for him to get through a few fights. I can see his career being kind of like Matt Hughes, just a strong wrestler early on and then finaly develpoing into an all around MMA fighter.
BTW, if Vera thought Aurresiro Silva was strong he wouldnt know what to do when a guy like Lesnar bear hugs him against the Cage.