Brock Lesnar isn’t announced for Extreme Rules at this point and it was noted in the Wrestling Observer Newsletter that the plan for Lesnar’s next Universal Title defense is SummerSlam but even that isn’t set in stone at this point.
Brock Lesnar could always go back to the UFC because there would be big money there and even less time on the road as hard as that might be to believe. But he still needs to serve out a suspension that was frozen when he “retired” from MMA and there are still 6 months remaining on that.
It was noted in the Wrestling Observer Newsletter that they cut off for Lesnar at this point to make a return to UFC by their New Year’s weekend show is June 30th. Therefore, if we don’t see Brock Lesnar re-enter the USADA testing pool making himself eligible for random drug testing by the 30th of June there’s a better chance he’ll be sticking with WWE or he could use both companies against each other and negotiate an even larger deal.