Since The Undertaker's retirement after WrestleMania, Vince McMahon had told WWE's commentators on several occasions not to reference The Undertaker too often. However, in recent weeks, there has been a reversal and McMahon has told the commentators that it's now okay to acknowledge The Undertaker when it's called for.
Romain Reigns has been encountering "Undertaker" chants from crowds aiming to taunt him and it's clear that while the Undertaker is gone for now, he has not been forgotten. There's more to the story though, as McMahon's directives to the announcers were not simply done out of the blue. In recent weeks, there has been communication between Vince and The Undertaker that leads Vince to believe The Undertaker would consider wrestling at next year's WrestleMania.
While it's by no means a foregone conclusion, all previous conversations since WrestleMania had left McMahon feeling like The Undertaker would never wrestle again, until the most recent talks, which now have McMahon feeling like The Undertaker has left the door cracked open. For this reason, those close to Vince are convinced it can't be a coincidence that he's had a change of heart in terms of The Undertaker being mentioned on air.