In a perfect world, I shouldn't have to be hinging my hopes on just Bryan to win the Rumble in order for me to consider the event a success. If the WWE creative team was an actually competent creative team, there would be several characters in the rumble who wouldn't look out of place to win the Rumble and main event mania. Alas...
Mulling it over for a bit I think Reigns got this in the bag. Cena ends up feuding with Rusev because he interferes in the trio match, Rollins doesn't cash in at all, and Brock ends up wrecking the two on Sunday. Bryan? Probably gets eliminated by his Wrestlemania opponent. It'll be Reigns vs Lesnar in the Main Event, and before that, he gets a big tune up match on Fast Lane by beating Cena in a 12 minute main event match. The night after Mania, Rollins finally decides to pull the trigger after Lesnar asks for a rematch for his belt against Reigns, and Rollins cashes in successfully. Rollins is champ all the way through Summerslam where now everybody can enjoy a nice dynasty reign by Reigns. XD