The working idea right now in WWE as it pertains to Sting is that he will do one match and then retire from in-ring competition. As of right now, everyone seems to be under the impression that the one match will be against The Undertaker at WrestleMania 31 in Santa Clara. Sting has reportedly been studying tapes of Undertaker matches, leading many to believe that he is under a similar belief.
Whether the idea for this match is made clear at WrestleMania, RAW the next night or at some point closer to the actual show is unknown. As of right now, the only thing that seems to be for sure is that Sting will only be doing one last match, likely against Undertaker.
As far as his contractual status with WWE, nobody has confirmed that he has actually signed at this point, although the feeling seems to be that it’s an inevitability.
(Credit: Wrestling Observer Newsletter)