I know these are just thoughts/predictions, but as to the OP -- I doubt Morrison would be there since it's the same weekend he has his DGUSA match.
I could see Mark Henry returning, and really just about anyone from the Q&A panels that weekend (Nash, Michaels, etc.) unless they do only have them in attendance for the Q&A sessions but keep them out of the actual PPV. I could see them being possibilities, though. Could also see Y2J or Christian returning.
My thing is wondering who they will have appear at next week's 20th anniversary show vs. who they hold to have as surprise entrants for RR. Two consecutive weeks of surprise appearances could make it interesting as far as who shows up when.