It's over and should stay that way for several reasons:
1) murray doesnt want to do it, and no one else is very enthusiastic. lack of feeling will create a crappy movie guaranteed. no way around it.
2) script problems: the original ghostbusters as dan wrote it would have sucked something awful - in the least, it would be totally different from the GB we swa in 1984. The same goes for some of the original concepts for Ghostbusters 2. Dan seems to be good for ideas, but his ideas need significant refining. I am always terrified when reading the final script at how bad the movie would be if it followed the script to a T.
3) Ghostbusters should have been its own movie. It appealed to everyone because we were all starting on the same level. we know about as much about ghostbusting as our three leads, and it becomes a going-into-business movie (in addition to being a buddy movie). The ghostbusting takes almost a second role to the love story that is going on and the overall plot; we only actually see one bust. And in the end, it appeals to everyone. The second film was like an episode of the cartoon, and only appealed to fans and sci-fi buffs. It had a definite repellent for people who arent into the genre. The first film works on a number of different levels. The second film appeals to a specific genre, and is harmed by that.
GB3 should stay dead; sequels are always inferior to their predecessors (with VERY few specific films, like The Godfather).
nick