#3: Kurt Angle

Kurt Angle's days in the ring in the numbered and it would appear as though his current storyline is heading towards his retirement in the near future.
Choosing Angle's final opponent is tricky. In his heyday, Angle was one of the best wrestlers on the planet, and given the right opponent, there is no doubt that he could put on one last classic on his way out.
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With that in mind, Zayn could turn out to be a perfect choice. Zayn is one of the company's most capable in-ring performers and is more than capable of carrying a veteran like Angle to an excellent encounter.
The WWE even have the option of playing this off as a heel vs face dynamic, with Zayn returning as the same character who left, or a face vs face one, with Zayn challenging Angle out of respect.