Now it appears that the answer is clear.
...

It seems that with one week left until the big payoff for the "break the code" promos WWE has decided to lay their cards out on the table. With much clearer messages like 6_Days, 23_Hours, 33_Minutes and of course Next_Monday they have let us know that yes, it will all be revealed next Monday. With other messages like X + 1 = Y, J = 9 + 1 ^* and of course BREAK_THE_WALLS instead of BREAK_THE_CODE have let us know that yes, it is Chris Jericho coming back.

Maybe it is the heel in me, but with this clear communication being used to drive up live viewership, it would be awesome if it wasn't Jericho. The date is still important, but having anyone else come out would be a total swerve. It would have to somehow make sense, and it would have to be someone with a powerful persona and presence. The only thing I can think of would be the Rock, but I don't think that is or even should happen. He's got a decent acting career going on and he has enough credibility now to do some decent films.

All the smarks out there need a good shakeup. It would be better than when Test faked an injury to win a match, and the services of Stacy Keibler. They made it look real, with all the "secret signals" from the refs to the back. I think the doctor even came out. It was a thing of beuty. On a lighter level they could tease the swerve early on in the show with any other wrestler who hasn't been seen in a while. Then in the last half hour of Raw, have Jericho actually return and show us the truth behind the code, while having him take out this lucky wrestler who gets a massive heel push with all his signature moves. That's it, close the show and good night :)

When he comes back, maybe it will look like this:

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^*Where's the 2 in Y2J? If they thought about it, which is a high probability
X + 1 = Y: X is the Roman Numeral for 10. 10 plus 1 is 11. 1 + 1 is 2
J = 9 + 1: 9 + 1 = 10 and there are 10 types of people in the world.