Its speculation whether the CoC is still Sheo and will forever be until Beth gives a definitive answer. Its speculation. If you want it to be, then it is. If you don't, and want to say any other theory, then it is, because Beth doesn't involve themselves in pc canon. Nor do they when they give vague accounts of what happened to previous Heroes.
Beth absolutely involves itself in player canon. Almalexia calls the player out as the Nerevarine in Tribunal. Heck, we even know the Nerevarine went to Akavir after all the drama was over. What the player
does is used to create the next game or expansion in the franchise. Who the player
is at the beginning of the game is something Bethesda doesn't touch. Gender, age, race, backstory... all of that's a mystery. All of their acomplishments? Not so much.
Spoiler Skyrim's Sheogorath directly states he was present for the entirety Oblivion - "You know, I was there for that whole sordid affair." Don't forget that the CoC was the only person present when Martin turned into a dragon. If the CoC did pass his title over to another, the recipient was his own shadow.
-sighs- So many edits. So much 6am.