Bruce Prichard recently spoke with Newsweek about The Undertaker retiring from the WWE and noted it will be a mutual decision between The Undertaker and Vince McMahon. 

"It’s a mutual trust between two men in that The Undertaker is the guy who has always been there. He never threatened to leave, he never held it over Vince’s head when everyone else was leaving in droves. Taker was the one on the front lines. He was the one guy you can count on that when everything was breaking down he was going to stand there steadfast and fight to the bitter end, no questions asked. You didn’t have to ask for his loyalty. You didn’t have to ask “if you’re with me.” That’s just the relationship between him and Vince. It’s a mutual trust and friendship. Sometimes it’s a love/hate situation, but the basis is based on respect and love. Both of them trust the other one and will do anything they can for each other.

I think he’ll let Taker decide on his own, but I guarantee you that it’ll be a mutual decision. I think it’ll be a decision that they’ll discuss and mutually agree upon. If Vince thinks he can get one more out of him or Taker feels he has one more left in him, the other will respect that and make it work."