There has been nothing official about Undertaker retiring, but all the wresting news sites (for whatever they are worth) are reporting it as if it is true. He has been giving more and more interviews as himself, which he essentially hasn't done for 30 years, so there is definitely a shift there.
If he is retired he appears to be going out on his own terms, which is all we can really hope for, right? Maybe not perfect, or how he envisioned it, but really, what big name wrestlers have had the ideal retirement? Flair did after WM24, but that didn't last. Michaels did, till he had that match recently than no one wants to acknowledge ever happened
Regarding the Mankind/Rock match, I thought it was established that Rock let the moment get away from him with all the unprotected chair shots, and has since apologized to Mick, to which Mick accepted the apology with no hard feelings.