I'm kind of iffy of putting him in the World Title picture, as Goldberg likely would not have existed had that happened.
I can make that work.
-Have Bret appear for the first time at Starrcade 97. The nWo is beating down Sting when Bret Hart makes the save. Hogan is able to escape and a tense staredown between Hart and Hogan is shown.
-The next night Hart comes out and says that it's time to restore wrestling's credibility, and it's time to hold those accountable who are ruining the business. (Which leads to him running down Hall and Nash, then running down Hogan)
-Continue the build toward the February PPV SuperBrawl 98. SuperBrawl 98 is headlined by a Hart vs Hogan World title match. Make sure Hart doesn't wrestle before the PPV. Hart wins the World title with a massive celebration afterward.
-Hart drops the title to Hogan in a rematch at the Great American Bash 4 months later.
-Goldberg (US champion) wins the World title from Hogan the following month at the Bash at the Beach PPV.
-Everything else with the World title from here stays the same. (From Goldberg to Nash back to Hogan)
-After losing the World title, Hart reforms the Hart Foundation with Jim Neidhart. Together they win the WCW World Tag Titles from Scott Hall and The Giant. They hold the titles for several months. They lose to (whoever) right before the fingerpoke of doom.
-Right after the Fingerpoke of Doom, Bret Hart cuts a promo on Hogan, Hall and Nash for attempting to ruin the business again. (They can show the exact promo Hart cut on those three when he first came to WCW to tie everything together) He vows to stop this once and fore-all to restore the credibility and integrity of professional wrestling.
-Hart/Hogan World title is set up for SuperBrawl 99. Hart wins the title again, thus finishing off the nWo forever in the process. Hart stays as a face for the rest of his tenure in WCW.