As we mentioned in the PWInsider Elite section, Undertaker is expected back on TV shortly, possibly as soon as Monday's Old School Raw.
Undertaker vs. CM Punk was confirmed for Wrestlemania about a week ago and WWE Creative is now scrambling to fast-track the match's storyline. They started phase one with Punk's promo on Monday referring to himself as an "icon" above Superstars and God.
One concern within some facets of creative is that with Punk having lost two PPVs in a row and again to Cena, that a loss to Undertaker at Wrestlemania could really damage one of the two names who show they can draw on the road currently, the other being John Cena.
Source: PWI
As it's PWI I'd say there's a 99% chance he's going to be on RAW this Monday. I have to say, I also saw Punk talking about being the best and God etc. as the queue to begin the Taker feud, seems I was right.