Ryback's appearance at the end of this week's episode of RAW from Albany, NY, in which he stared down CM Punk, was a last minute decision.
The final rundown that was given to the top production people didn't feature Ryback as the show went off the air. This is part of the reason why it wasn't shown on the Titantron to the live crowd. It was a last minute decision on how the show would conclude with officials having the attitude of "let's do it and we'll figure it out later."
There is no plan in place for Ryback and CM Punk, it was just put together to see how it would be received. Of course, if John Cena isn't ready to face CM Punk at Hell in a Cell, the seeds have been planted to insert Ryback into the match as a replacement. That's pretty much the reason it was done - as a backup plan.