What if Flair had stayed in WCW in '91?
I'd guess that Sid would be placed in his role, winning the title at the rumble and losing at mania to Savage. Meanwhile, Hogan would feud with Taker and Jake, leading to a tag match at WM. Hogan's mystery partner would be Warrior, who pins Roberts. The Savage-Warrior-Perfect angle still happens more or less, while the Undertaker, who's still a heel, feuds with a top face (let's say Bossman). Taker beats Savage soon after the ppv, leading to UT/Razor vs Savage/Perfect at Survivor Series. Taker probably jobs to Bret sometime before mania, though they could have UT beat Hart at the show and have Hogan get his cheap win.
As for WCW, who the hell knows. It would be cool if The Dangerous Alliance formed anyway, leading to Flair being betrayed by Arn and the other Horsemen (I'd switch the roles of Windham and Eaton) and having to crawl back to Sting and friends. Since Sting's an idiot, he takes him back and they become friends again. Of course after the DA is defeated, Flair returns to his old ways.