dan akroyd( and I think Harodl Ramis) completed a script which involved a Hades version of New York. The studio rejected it!
this is wikipedia so there may be some basic errors in it but i think this basically sums up what was going on with it
uture film
Ghostbusters III is a proposed project. During his interview with Mike McGuire on CISN Country 103.9 FM in Edmonton, Alberta, Dan Aykroyd announced that Ghostbusters III: Hellbent will be CGI. "I can do all the things I wanted to do for much, much less money," he stated. Aykroyd wrote the script, which was described by IGN as being "too technical", with a new team of Ghostbusters that were not clearly delineated and had no group conflict or leading personalities.[19] Bill Murray has been thought to have held up the making of a third Ghostbusters movie, despite Aykroyd's enthusiasm, due to his desire not to do another live action movie and his dislike of sequels.[20] However, he has now signed on to make the movie now that it will be CGI.[21] Harold Ramis is already attached. Sigourney Weaver has not expressed enthusiasm at doing another sequel.[22] Harold Ramis mentioned in 2005 that he wanted Ben Stiller to take Bill Murray's part in the then titled Ghostbusters in Hell.[23][24] The plot was to follow the three Ghostbusters attempting to find a replacement for Bill Murray's character while dealing with ghosts rejected from hell.[25] Aykroyd later elaborated, now that Murray is on board, that in the movie "We go to the hell side of Manhattan, downtown, Foley Square. It's all where the cops are--they are all blue minotaurs. Central Park is this huge peat mine with green demons there, surrounded by black onyx thousand-foot high apartment buildings with classic red devils, very wealthy. We go and visit a Donald Trump-like character who is Mr. Sifler. Luke Sifler. Lu-cifer. So we meet the devil in it".[26] Jason Reitman, the son of Ghostbusters director Ivan Reitman, has stated that he has little interest in directing the movie.[27]. He was a guest on The Howard Stern Show on April 10, 2008; when he was asked if he would direct Ghostbusters 3 and cast Howard, he said "do you know how many times I get asked if I want to do Ghostbusters 3? Looking at my career so far, I mean if you just looked at my two films, I would make the most boring Ghostbusters movie. It would just be people talking about ghosts, there wouldn't be any ghost-busting in it." Recently, Ernie HuRABon told Moviehole.net, that Ghostbusters III is still very much a possibility. He said he hoped that the new video game would generate renewed interest in a 3rd Ghostbusters film. [28] The February 2008 copy of Total Film magazine has stated that the game will use the plot devices of the third film, quoting Aykroyd as saying, "This is essentially the third movie". All old cast members have been signed on to the video game aside from Rick Moranis and Sigourney Weaver. [29]
In an interview with Gameinformer, Aykroyd stated that the up coming Ghostbusters video game would be "as closest to a third movie that you can get."
the fact that they are all older, grey and fat but still ghostbusters is more exciting than having a "new breed" of ghostbusters and appealing to a new audience. I dont think they need to do that, because look at what happened with star wars - there is no need to appeal to a younger audience because there are enough older people who want to see it and younger audiences would check it out anyway.