4. CM Punk
Yes, CM Punk walked out of WWE in January, and yes, there's no shortage of acrimony between the two parties. On top of all of that, Punk has taken to life outside the ring well enough that he's showing no signs of wanting to revisit his former career. Nevertheless, the one thing that could potentially draw him back into the fold -- at least temporarily -- would be a feud (and a WrestleMania main event) with his childhood icon, Stone Cold Steve Austin. What would WWE get out of entering into negotiations with Punk? Arguably Stone Cold's ideal opponent. Both men have expressed interest in working with one another, and during a sit-down interview to promote the WWE '13 video game a few years back, the fur between Punk and Austin flew in compelling fashion. Just a few moments of watching those pros work together -- even verbally -- had the internet clamoring for the match. Imagine Austin is hyped as the guest host of Raw the night after the Survivor Series. The main event needs a troubleshooting referee, so Austin steps up to the plate. Everything goes down smoothly, but after the match, "Cult of Personality" hits! The stunned crowd erupts, but their cheers turn to shock as the returning CM Punk decimates Austin, beginning one of the greatest blood feuds in either man's career.