I disagree in that he shouldn't have come back. He probably should have ended it before the next WrestleMania though.
Repeat what happened at the show of shows and have Lesnar win then go after the title, every time he gets close the lights go out and he's laid out courtesy of The Undertaker. Lesnar flips, says he'll kill The Undertaker etc etc, Taker' does his usual shtick, buried alive match only Bray Wyatt should have been the one filling the whole as the new face of darkness or whatever which would have led to Lesnar v Wyatt for some silly reason.