I don't think you can say "oh yea, you can easily replace Hogan or Flair" (I'm sure most of you will say you could easily replace Hogan

), but think the companies could have achieved at least the success they did with other wrestlers. Vince was very smart back then and knew how to market his product. He would of found somebody else to make as the top star. And that guy wouldn't of had to take on the Hulk Hogan charcter or anything. He could of done something completely different.
With the NWA, you had so many good workers back then. I could easily see a Tully Blanchard being the man in Flair's spot just as an example. But if you were to really sit down and analyze the NWA roster (including all the territories), you'll soon realize you could survive without Flair. The NWA had a quality product all across the cards back then.