I think that post-WM3 story was a complete Hogan lie. Sting wasn't even a big star in NWA/WCW yet when Hogan claims he wanted bring him in and just pass the torch and everything to him. Hogan reaches his peak at Wrestlemania 3, gets the biggest reaction of his career there when he body slammed and defeated Andre, and yet he wants to turn heel and give it all to an unproven talent? This is a guy who wouldn't even put over Sting cleanly as a HEEL the three or so times he faced him when he (Hogan) was past his prime in WCW, never mind his prime and peak in '87.
Also, Sting wanted to jump in 2011 (said so himself in a radio interview) but Vince wanted him to work a full schedule instead of a part-time one so he signed another contract with TNA. If the story posted in this topic has any truth to it, maybe Vince has re-considered and wants an Undertaker/Sting match at Wrestlemania XXX.