Fans have been speculating about a heel turn from Dean Ambrose for some time now. Hell in a Cell may be the perfect opportunity for this. Let's assume that both The Shield and Ziggler and McIntyre somehow find their way into the dreaded structure. And then Ambrose turns on his brothers!
This makes a lot of sense because it would keep Reigns strong, while getting the Universal Championship off his waist. It would also lead to a Reigns vs. Ambrose feud, something we've not really seen before. Sure, they have wrestled one another, but never in a full-fledged, all out program.
Ambrose may be upset that he's the only superstar without a Championship in The Shield. He may also want a fresh coat of paint for his character.