As everyone saw on RAW last night, Triple H brought up The Undertaker’s absence during an in-ring promo and stated that "The Streak" ended at WrestleMania 27 because we haven’t seen "The Deadman" since. He also said 'Taker wasn't able to leave the ring on his own at the pay-per-view.
In an update on this, current plans call for Triple H vs. The Undertaker to be one of the top matches at WrestleMania 28.
There are also plans to do a Chris Jericho vs. CM Punk match for the WWE Title at the event. Of course, The Rock vs. John Cena is also scheduled. These are the three top matches planned as of this writing. Of course, things can change so stay tuned.