Re: who should have ended Goldberg's Streak?
Before I give my answer, I'd like to offer my take on some of the names suggested thus far and why they would've been poor choices.
DDP - Too old. DDP was 42 years old in 1998. Ending Goldberg's streak could have made an instant main eventer - which Nash already was - and even though DDP was over as hell, there wasn't much of a future with him (this is of course working under the assumption that if you were booking WCW in 1998 you didn't have a time machine to predict the company would be dead in three years).
Jericho - Should he have had a feud with Goldberg? Absolutely. The months of segments of Jericho mocking Goldberg on his own were television gold; it's sad to think about how much entertainment we were deprived by the Goldberg/Jericho feud never happening in WCW. But, end the streak? No way. He could have never won clean in any believable fashion. And even though a chickenshit heel victory would've been great for Jericho - and certainly a better alternative to what they did with Nash - I'd still consider a waste of what they'd built with Goldberg.
Sting - Sting shouldn't have beaten Goldberg for the same reason that Triple H shouldn't have (and didn't) end Undertaker's streak: he just didn't need it. Sting couldn't have been any bigger of a star than he already was in 1998. Hell, he was on the decline at that point; 1997 was his career apex, which is amusing considering he only had one match all year. There was no long term, or really even short term, upside to Sting beating Goldberg.
Benoit - Of all the names I'm listing here, I'd consider Benoit to have been the best choice of the lot, even though I wouldn't have had him end the streak either. The guy who beat Goldberg needed to be someone who could be a top star, and Benoit just wasn't that guy. He lacked the charisma and the presence to be a main eventer in 1998, and even though I think he's the greatest technical wrestler ever, I feel that was true of his entire career.
Bret Hart - See Sting.
So, who would I have had end it?
It almost shocks myself that I'm saying this, because I was never really a fan of the guy at all - well, except for making fun of his oftentimes incomprehensible promos - but I think it's the best possible conclusion:
He had everything WCW needed at that point. He already had the name recognition from all the success of the Steiner Brothers. He had the talent. He had the charisma. God knows he had the look. A competently booked WCW moving into the 21st century with Goldberg as the top babyface and Steiner as the top heel would have had a lot of potential going up against all the zaniness of the WWF. There is no one else in WCW at that time who was a better choice to beat Goldberg than Steiner, and I was never even a fan of the guy.