Shawn Michaels as the 3rd or 4th member of the nWo would have been amazing (either an amazing coup for WCW, or an amazing train wreck. Not sure which.)
So many fascinating possibilities:
-- Does the nWo angle become even hotter or does it burn itself out quicker? (I'd guess it does even better business)
-- Do you still turn Hogan? (Probably. They were willing to turn him because his babyface act was getting tepid crowd responses by that point)
-- Who wins the backstage power struggle? Can the Kliq and Hogan co-exist backstage?
-- If they can't, is Hogan expendable? Does he try to go back to Vince?
-- What becomes of Shawn if he doesn't suffer the injury in '98 and retire? He's said the injury led him to getting clean and being born again. Does he give up the drugs in WCW? (Probably not)
-- For that matter, does he wrestle at a high level in WCW? Or does WCW sign another Davey Boy Smith (drugged out shell of himself)
-- What about Sting? Do you still go the Crow Sting route? (probably. That had at least as little with Sting working more dates than his contract called for and WCW wanting to cut down his appearances to save some money)
I wish this had happened. After Hogan came in, WCW kinda transitioned away from the workrate promotion they were in the early 90's, but there were would have been a lot of fresh matchups. HBK vs. babyface Flair would probably have been amazing. Surfer Sting vs, mid-90's heel HBK is one of my personal dream matches. And, if you still turn Hogan into Hollywood Hogan, you do heel Hollywood vs. face HBK somewhere down the line.