I think if WCW had returned to prominence instead of going under, there would have been many more events of interest born out of the natural rivalry between the two companies and the movement back and forth of wrestlers continuing.
The thing is, until a day could ever come that another North American company could reasonably and viably compete with WWE, the signifigance of WCW folding remains more speculative than concrete. "Wow, imagine if WCW had come back to being competitive!" is a discussion that can't happen until another challenger emerges.
...and, for the record, I don't see that happening anytime even remotely soon, or even further down the road. So the folding of WCW will always be on the back-burner in terms of how fans think of it's impact.