I'm actually hoping for no one to turn and join Nexus. I think having someone like HHH or Bret Hart or whoever suddenly join them wouldn't make sense and really, I don't think they need it. It's been mentioned that apart from Barrett, the members of Nexus aren't too well-known and having an established star join their ranks would take the focus off the original members IMO. I'd like to see a heel Cena too, but having him join Nexus after what they've done would just be

.
I'm hoping for Nexus to win the match relatively cleanly but I'm guessing some kind of shenanigans will take place. This angle's one of the best things they've done in recent years and a Nexus win would help continue it I think.
I really hope they don't go down the route of 'Bret Hart turns on WWE because of the Screwjob (despite the fact he's made peace by making up with Shawn and beating Vince at Wrestlemania)'. That would be crap....