Just to reminisce about "What Could Have Been", I keep thinking how Sting vs HHH would have made for such a great rivalry if Sting had joined the company in 2003. That was the year that Hunter (during his infamous "reign of terror") was running through every former WCW wrestler (Scott Steiner, Booker T., Kevin Nash, Goldberg... although he at least dropped the title to Goldberg for a few months), so who better than Sting, WCW's franchise player, to come in and challenge and finally beat HHH for the World Heavyweight Championship, a title that was designed in the likeness of the old WCW World Title (i.e the Big Gold Belt.)
Add in the fact that Evolution was sort of a latter-day version of the Four Horsemen (whom Sting had history with) and Sting's greatest nemesis Ric Flair was right there by Hunter's side as well, and you would have had the quintessential feud for both men at the time. One more Sting/Flair match wouldn't have hurt, and Sting vs Orton would have made sense for the fact that Orton would have his sights set on another legend to kill.