There are still lots of rumors surfing around on Internet about the mystery partner of Roman Reigns and Dean Ambrose.
First it was said that it will be Randy Orton after we saw an on screen talk between these three. Going further Randy was beaten down by the Waytts. It made the rumors strong that he can be the partner. But soon after news came in that the angle was done to give Randy some time off.
He recently talked to WWE management for a lighter working schedule going forward. He was backstage at the season premiere episode of the Raw but was not used. It makes the speculation strong that he will not join Roman and Dean.
A little rumor of Eric Rowan joining in was also spread but PWinsider is reporting that it's wrong. He hasn't recovered completely from the Injury yet. He is supposed to take some more time off from the ring. He will report to WWE performance center soon. He will work there sometimes before getting back into the ring.
The other two names are Kane and Chris Jericho. Kane has been out of action from quite sometimes now for not known reasons. If he does return, it will make a good match as it will fulfill the "Monster vs. Monster" element in the storyline against Braunton Strowman. Chris Jericho on the other hand is working with WWE continuously on live events and he can possibly make a one night only appearance for the ppv.