Granted this is the most far-fetched possibility of them all, but hang with me for a minute.
The Rock and the Undertaker have had numerous battles throughout the years, but never at WrestleMania.
Next year, the Undertaker would be going for 20-0, and possibly retiring after.
Next year, WrestleMania emanates from Miami, which is The Rock's hometown.
Show me a bigger money match than The Rock vs. the Undertaker at WrestleMania 28.
Now, for the 13 people still reading this since it is sacrilegious to suggest that the streak will end, I'm saying that he attempts to help end the streak; not end it.
Under this scenario, The Rock would for example, Rock Bottom the Undertaker after the Undertaker has hit the Tombstone on Triple H. Therefore, the Undertaker would still be able to kick out of The Rock Bottom and go on to preserve the sacred streak.
Given the time off necessary for both The Rock and the Undertaker, this feud would be able to last a whole year.
Also, if the Undertaker were to take his usual few months off after WrestleMania, it would still give the Rock time to finish his feud with Cena.