5. Chris Jericho
As he has proven time and time again, Chris Jericho always has a surprise up his sleeve and as his New Japan Pro Wrestling appearance highlighted, he is not tied down to specifically working with WWE exclusively anymore, meaning he could realistically appear at ALL IN.
Jericho is working alongside Ring Of Honor for his cruise this year, which is going to feature a lot of talent that will likely be performing at ALL IN, yet again showcasing Y2J branching out into the world of the independents and this could be his next step.
Seeing the buzz that Jericho created for Wrestle Kingdom 12, it must have crossed the minds of Rhodes and the Young Bucks that he could easily do the same for them. Not to mention that Jericho would make the perfect partner for Kenny Omega in a highly anticipated rematch.