According to The Wrestling Observer, The Undertaker vs Brock Lesnar is officially on the books for WrestleMania 30.
This is the match that will take place at the big PPV, provided Undertaker is healthy enough to work a Lesnar-style match.
The plan all along in WWE was for Undertaker to face either Brock Lesnar or The Rock, and with the likelihood of The Rock not working the PPV becoming more realistic, it appears as if Lesnar will be 'Taker's opponent next year.