You must've heard the rumors that Hulk was within inches of re-signing with WWE back in '98.
Assuming it wasn't just a ploy for leverage on his WCW K would it have been the greatest thing ever or the worst?
1. For WCW, I imagine it would've killed their progress dead. Hulk had never REALLY gotten his comeuppance and if he left before putting Goldberg over, there probably wouldn't have been anyone to be the face of the company outside Savage (?).
2. WWF? I don't imagine Hulk could've really adjusted to Attitude Era with it's super fast matches (both in length and speed) and shoot-centered promos. That said, there's no way having the 2 biggest names in the business under one roof couldn't have shot WWE to at least short-term amazing heights. You also had ready-made feuds with UT/Kane. Of course, Hulk would've distracted from the Austin/McMahon feud, probably leaving his net benefit at a neutral (or negative, considering he'd be coming under a Seven-figure deal at least).
Still, ripping out the heart of your competition right at the start of your life and death war might have thrown this one right in the win column for WWE no matter how much of a distraction Hulk was.
I don't think it ever would have happened. Hogan was demanding too much money, and at that point you're trodding on the ego of Steve Austin the moneymaking machine, who I cannot see sharing his spotlight with Hulk. Plus it probably would have killed off Rock, who was not the kind of guy to play politics and would have deferred to Hogan and probably ended up the worse for it. I just don't see it, to be honest.
That being said, were it to happen, yes, that would have ripped the heart out of WCW, so I can see Vince doing it anyway.