I've said this a few times before, but if Carmelo ends up in the Eastern conference then the East could end up being the more dominant conference for the next few seasons. The Magic, Celtics, Hawks, Heat, the Knicks, and whichever team Carmelo was traded to (if it wasn't one of the aforementioned teams) would all be playoff-level teams, similar to all of the quality teams in the top 8 of the Western conference. I'm not saying that's a bad thing, or that I don't want to see Carmelo in the East -- in fact I would be in favor of the East becoming the more dominant conference like they were during the 90's when the East won the Finals 7 times.
If the question was whether or not the Bulls, after adding Carmelo would be a threat to win it all, I'd still say that it depends, but either way it doesn't hurt the Bulls franchises' legacy to add an all-star scoring specialist to their roster as Carmelo would likely be the most talented scorer to play for them since Jordan retired. Now I'm not trying to compare 'Melo to 5-time NBA MVP Michael Jordan (heck, Jordan is going to be on the cover of NBA2K11, and not 'Melo, despite the fact that MJ has been retired since 2003) however you certainly don't have to have a sort of 're-incarnation' of Michael Jordan on your team in order to win an NBA championship, as these past 7 years of LeBron James basketball career have proved.