Hogan was an international star long before Vince lured him from Gagne. Vince pushed him to another level that I don't think Gagne would have been capable of, because only Vince had designs of going national. With that said, somebody was eventually going to split from the establishment, exploit cable, and make a go of it (Joe Blanchard actually tried it first, as a lot of people forget that he was on USA Network long before WWF).
Vince had no faith in Austin, to the point they hated his promos so much that they wouldn't let him talk. Austin largely made his own break by creating the Stone Cold character (basically because the office didn't care because he was just a mid carder), and cutting the 3:16 promo. But if you remember, it still took months for them to get behind him. Eventually, they had no choice, he got over on his own.
I will give them credit for The Rock, who they found (well, he came to them) and developed, but even with The Rock they misread the fans and tried to push him as a smiling cornball babyface. If he hadn't been persistent, he might have quit (think: Maven, Lashley for examples).