WWE isn't pretending that the Undertaker is immortal. They fully recognize and acknowledge that he is getting older. And they've done an injury angle with him before, with the Shield taking him out last year. With Taker facing former UFC champ Brock Lesnar on Sunday, look for Brock to "injure" the Deadman during the match. Maybe Brock locks in a kimura and "breaks" his left arm, but Taker still manages a chokeslam or Hell's Gate somehow and pulls out the win. Afterward, Undertaker limps out of the ring, only to return the next night to say that Brock took him to the limit and that his battered body might not have another match left in it. That keeps the Streak alive, gives a nod to Brock and covers for another long absence from Taker.