Rey Mysterio returned to the WWE after a long time away during the Royal Rumble match, making it into the final four. It was then rumored he would sign a part-time deal where he could come and go as he pleased, similar to Chris Jericho's.
John Cena is currently in a storyline where he's desperately trying to cement himself a match at WrestleMania had has entered the Royal Rumble, appeared in the Elimination Chamber and is now going to enter the Fastlane main event.
Justin Barrasso is claiming that Mysterio is about to cement a WrestleMania match deal with the WWE and that the opponent that is rumored for Mysterio is John Cena.
This would make some semblance of sense as Cena was the person to eliminate Rey Mysterio at the Royal Rumble, but it would definitely be a dramatic departure from the rumored Undertaker match at WrestleMania.
Breaking: Per WWE sources, Rey Mysterio is backstage working out details tonight at SmackDown for a match at WrestleMania. The rumored opponent is John Cena.— Justin Barrasso (@JustinBarrasso) February 28, 2018