I'm gonna be realistic and say...
He would've had a few more years in the midcard, played a key role in the invasion angle during which time he would've also gotten a main event push assuming he didn't get injured.
He wouldn't have gone to WCW, he had over a year to follow Bret and he chose not to.
Whether he would've won the WWF title or not is a tricky question. I personally think he would've played the role Angle did when Angle was in the Invasion. He would've had a very personal feud with Austin after Austin defected to the alliance, because as well as Angle played the role, Owen would've played the 'WWF's most loyal member' role better because he had been there so long. i'm thinking he would've been given the WWF title eventually, but when it had been renamed WWE. Because after Austin and The Rock had left, he would've been the only big name there other than Triple H, so he would've took control of SD. And I'm thinking a 2003 or 2004 retirement.