As noted a week ago, the current plan is to have The Undertaker face Roman Reigns at Mania. Well, there's a reason why this is happening. Fans will be behind Taker more than Roman Reigns as most people in the WWE Universe dislike Reigns. McMahon has been wanting to make this match for a very long time. Undertaker's health is declining and there's not much WWE can do to get fans to cheer for Roman. Taker is likely to not want to do this match next year, so now would be the time.
There's talks this match will be "passing the torch" to Roman Reigns. There's not a clear decision if WWE wishes to make Reigns a heel or not yet for this feud. It's seeming that long-term plans are to make Roman be the face of the company.