There were rumors back around Wrestlemania season this year that Vince was gonna challenge Donald Trump to a fight (lame as that would be) but I guess those rumors are false. However, they could always change up and end this McMahon family feud triangle between Vince/Stephanie/HHH before Wrestlemania XXX and just have all three McMahons on the show anyway but in different roles - Vince/Trump in some type of altercation, Stephanie and AJ working together (or Stephanie at least introducing a new Diva to take AJ down for the title, and Steph serves as the special guest referee) and Triple H wrestling someone. That seems more plausible to me. After all, who is Triple H gonna wrestle as part of the story line of him and Vince against each other? I guess Vince could pick out an opponent to take on Triple H (the idea being that if HHH wins, he replaces Vince as the Chairman or something) and they could work it that way or Vince could step up to HHH himself (no, just no) but I dunno.
The 'passing the torch' idea is interesting, but I don't see it going down that way. Maybe on-screen with Triple H somehow acquiring the main position of power but even then, how long can Vince really resist not putting himself back on TV? That same power of shift happened back during the Summer Of Punk angle in 2011 and look how quickly Vince came back and look who's in control now. Vince first intended to leave television for good in '99 and that lasted all of two months before he returned.
In real life, I don't see him handing over complete control of the company to anyone yet. He's stubborn and will run it for at least few more years at least. Who knows, maybe Vince will run it until he's well into his seventies.