I also believe this has Austin/Bret written all over it as far as putting someone over by making them look tough as hell after losing a (hopefully) bloody and hard fought battle goes. That type of booking matches Dean's character perfectly and is what they've built the entire rivalry with Brock around thus far, so I expect their match to be the supreme demonstration of it as well. I could even see Brock showing him a little bit of respect after, not a handshake or anything, but some sort of respectful gesture as if to say "goddamn, you're tough." I can also envision Heyman citing in a promo the night after that while Brock still doesn't like Dean, he's managed to earn The Beast's respect, something that hardly anyone has ever done.
I wouldn't mind certain shades of Taker/HHH from WM27 either, where the winner of the match still appears to have suffered more damage to the body despite pulling out the victory, and looks ironically more worse for the wear than the loser himself does. That type of booking could work no matter which way the match swings, though.
If they want to put Dean over though, I'm cool with that. It's a street fight with no rules, so a moment where Ambrose just snaps and unloads some twenty or thirty-something chair shots in a row to Lesnar's back until it's enough to finally keep him down would be quite a moment. Think Austin brutalizing Rock with a chair at the end of their WM X-7 main event, but worse. When Brock destroyed Cena at Summerslam, everyone was remarking about how many suplexes Brock brutalized Cena with in a row (16.) In the event that Ambrose goes over, people can be remarking about how many chair shots Brock had to be brutalized with (let's say 32 or something) in a row before he was finally a beaten man.