I think if you want another ghostbusters movie they have to restart the franchise. Take Batman Begins, and Superman Returns. Batman Begins had a very successful restart, why? Because it was reborn. People weren't really comparing this Batman to Michael Keatons, or Val Kilmer's they just wanted someone who could pull off that character's persona. Superman Returns failed, why? Because it was a continuation, and I think because it was a carry on of the original series, people were more likely to compare Brandon Routh to Christopher Reeve's character, although Chris was the only superman throughout the series whereas Batman had different actors in the role. You have to think that maybe ghostbusters could be successfuly remade if the right actors can be found who have the essence of the original actors who brought the characters to life.
Now if you took the original ghostbusters and had them replaced by new ones, would you really be as interested, would you really be able to watch a story without characters like venkman, spengler, stantz, and zeddemore. And going back to the batman, superman analogy, would you ever be comfortable with someone else other than bruce wayne, or kal-el/clark kent being batman or superman