-- As noted before, John Cena vs. Undertaker has been a planned WrestleMania 34 match for months but it remains unclear whether this will go down as an actual sanctioned match or whether the two will simply have a confrontation, perhaps building to a match next year. Undertaker for his part will definitely be in New Orleans and has been training for a match.
-- From Vince McMahon's perspective, he believes the audience already knows that 'Taker will show up and "this is the story that brings him back to kick Cena's ass." He also doesn't believe announcing an Undertaker return in advance will lead to more people buying the WWE network as anyone who is going to be a new subscriber would be getting it for the PPV itself.
-- This is said to be McMahon's "story" and he seems "very happy with it" as he is able to say that the fans are "invested in the mere chance that Undertaker will show up."
Source: Wrestling Observer Newsletter. Subscription information & prices available at f4wonline.com