John Cena, who is currently out of action with a shoulder injury, posted this teaser on Twitter:
https://twitter.com/JohnCena/status/697791625054048256
As noted, if Cena is able to recover in time then the plan is still for him to face The Undertaker at WrestleMania 32. Based on how fast Cena has been able to come back from previous injuries and the fact that this show is going to be their biggest ever, it’s possible that Cena can come back in time. If Cena is healed enough from his shoulder injury, then they could just have him appear on Raw for 3 to 4 weeks leading up to WrestleMania and just not have him do anything physical until the match happens.