Steph was always pegged as the heir apparent. Shane handled alot of the business end, while Steph has always been front and center in the creative end.
Steph is a Vince clone--she lives and breathes the WWE, and wrestling does not exist outside of the WWE bubble in her eyes, just like dad.
The man who can save wrestling form sports entertainment, is the man most hardcore fans can't stand--HHH. Unlike his wife, unlike his father in law, he has an appreciation for wrestling's history, and looks up to people like Ric Flair, Harley Race, Killer Kowalski, etc.
It will be HHH's company one day, and it will be interesting to see if his influence on Steph alters the direction a bit. But that day is a long way off, because Vince will never retire and will run the company his was until his final breathe.