I was thinking the wildcard would be Hangman since The Elite claimed he was their guy, but then they showed that vignette for Hangman on Collision and now I'm not sure. If he was the wildcard, they wouldn't have tipped their hand like that, would they?
Honestly I'm not sure. M&M probably not for the reason you said. Dijak or Ricochet would be great to see but I feel if they bring em in they have to win their first match and with the story JJ has been put onto I still feel he has to win and at least to go to the finals, so that wouldn't feel right.
But it's gotta be someone out of the norm or why 'wild card' it? I'd wonder if it could be Adam Cole to 'defend' his previous tournament win but he's not healed up last anyone heard so I doubt that too..