The idea of Undertaker working this year's WrestleMania is still up in the air, reports the Wrestling Observer, and definitive plans are being kept very quiet backstage.
As noted previously, Taker was spotted at a Nashville Predators game this past Sunday, but was not backstage at Raw the following night. Some sources are saying that Taker did have a meeting with Vince McMahon, however, while in town.
The Undertaker had major hip surgery and shoulder surgery, both in the past year, so it was very difficult for him to do any major training until those had recovered. The hip surgery prevented him from working lower body while his shoulder kept him from working the upper body. It was also said he had lost a noticeable amount of weight, which could be a result of a lack of proper training or could be taken as a sign that he's trying to get in shape for this April's event.
The current plans still have Undertaker facing CM Punk at WrestleMania 29 if he's healthy enough to do it, but Taker doesn't want to come back just to "fake his way through a mediocre match". Potential match options for Punk, other than Taker, are not yet decided or again have been kept very secret.
If Undertaker somehow can't work this year's WrestleMania, most are not thinking it means his career his over. Rather, they believe WrestleMania 30 would then be centered around his return and farewell match, as he will be 49 by then.