In recent years, there were internal WWE discussions of ending The Undertaker's Undefeated Streak at WrestleMania, but those talks never reached a point of being seriously considered.
During an interview with PWTorch Livecast, former WWE Creative write John Carle descrbied the level of seriousness.
During your tenure, was there any consideration for Undertaker losing his Streak to any of his WrestleMania opponents?
Carle replied, Yeah, we (the writing team) kind of talked about it. It was one of those things that was pitched, but it never really came to fruition.
Carle's entire Livecast interview can be heard here.