On a personal level, I'd love to see Brock wrestle Bryan, Cesaro (probably won't happen), Reigns, Jericho (won't happen), Orton (if he became a babyface again), etc.
I'd also love to see Brock and Ambrose go at it at least in a brawl or something. I know the following scenario wouldn't make sense with the way things are now, but imagine if Lesnar's role at the moment was simply being The Authority's personal one-time bodyguard who stood in-between Ambrose and Rollins the next time Ambrose tried to interrupt Rollins cashing in. Imagine that Brock dismantles Cena on behalf of The Authority to allow for an easy cash-in for Rollins, and while Seth hands over the briefcase to the referee to start the match, Brock stands watch waiting for Ambrose to come out and try and disrupt Rollins becoming champion. Ambrose, being the crazy and fearless bastard that he is, arrives and goes straight after Lesnar. He ends up getting destroyed, of course, but that's not the point - the point is that he was still determined and fearless enough to try and stop Rollins from becoming champion even if it meant instigating a fight with Brock Lesnar of all people. And it's fitting that of all the ways to finally stop Ambrose from preventing Rollins becoming champion, The Authority would end up relying on "The Beast Incarnate", Brock Lesnar himself. Would have been a good way to set up a non-title feud between Cena and Lesnar at Summerslam if they had wanted to go that direction.
