Well, we've got Tommy Dreamer appearing out of the blue to feud with the Wyatts so, idk. Everything's possible. Though there have been tons of Goldberg rumours this year...
However, I'm kind of expecting to see Daniel Bryan doing the "John Cena" surprise entrance (being the "mysterious number 30").
Though the ones I'd really mark out for would definitely be John Morrison or Drew McIntyre... AND CM Punk tbh...