I’ve noticed a major point of contention among fans is the idea of passing the torch from the originals to a new crew. I can see the concern, but honestly, if the torch doesn’t get passed, Ghostbusters will effectively die as a viable film franchise when it still has untapped potential to go for years and years (though perhaps not in movies). That said, I believe it can be done respectfully and entertainingly if it’s thought through.
Also, it really seems like a logical progression for the story. If I was doing it, we’d start with the crew preparing to expand from operating only in the upper north of the east coast, to a full on Ghostbusters Inc., with company branches world wide. They’ve got employees trained, offices built, equipment all set. At midnight at the end of the week, GB Inc. is set to go online world wide. The guys are getting older and as much as they love the job, it’s harder to perform efficiently. Ray convinces them to all go on one last bust together, however, as field agents (working GBs). Once GB Inc. starts up, they’ll act more as CEOs, with Egon and Ray spending most of their time in labs developing new things, Peter still functioning as the mouth of the company, and Winston helping to run the show, making sure everyone’s got their head on straight. Anyway, they get that last call and it’s emotional, because they know it’s the last time. HOWEVER, (cue the admiral) it’s a trap! The paranormal forces realize this is their last chance to do something to stop them or else NOWHERE will be safe for them! They do something to the Original GBs to incapacitate them (kidnap them, throw them into some sort of paranormal coma, etc.) When they go missing/out of commission, the GB Inc. grand opening is postponed and the team being trained to take over the original post (I’ll call it NY-1) goes into action to figure out what’s going on. They uncover possibly the greatest paranormal threat ever to mankind. As the OGB’s try to fight back from their current situation, the new NY-1 squad (of course with help from Janine guiding from her wealth of knowledge gathered from years with the team) starts to unravel the mystery/ mastermind behind the forthcoming paranormal menace.
…(insert awesome stuff)…
It ends with a last ditch attack from every available malevolent phantom on earth taking action against their biggest threat. Reports would come in and Janine would take the initiative, calling everyone into emergency action from the NY-1 HQ. This is where we’d get a killer montage of all Ghostbusters crews all over the world fighting back! Ectos blazing streets in London, Tokyo, France, Russia, Africa, America! GBs of all ethnicities holding back ghouls and filling traps non stop! GBs busting up into houses to stuff Boogiemen back into closets, forming perimeters around graveyards, throwing down with evil spirits in the streets! Ghosts of all different kinds from different places according to the local legends of the area.
Of course, since these are basically just extras with proton packs, who better to use than the fans?! We’d do it for free, we’ve already got the equipment and uniforms, and all the acting it would involve really is running, yelling, and shooting! That’s something that could be organized through signing up at comic-con and then a small crew would come down, film the part, and that’d be that! For all the world to see for the rest of history, we’d be REAL Ghostbusters!
Anyway, that’s just fanboy dreaming.
We’d see cool new equipment like the garbage truck traps seen in RGB and EGB. Of course, when the big main villain is uncovered, the OGBs would wake up/ are woken up (new smart kid spends time working on an invention Egon didn’t finish and finishes it, using it to wake them up/bring them back?) and they would come back in time to take him down as the new GBs hold off the other ghosts. It would end with GB Inc. opening. That way, if they wanted to not do anymore movies, at least the story ended on a great note: The OGBs are still active in the company and there are now Ghostbusters watching the shadows all over the planet, so that whatever is in the darkness stays there, otherwise, they have a nice place for them 
OR, they could continue the story in either more films featuring the NY-1 team with cameos by the OGBs, or maybe even a live action TV series like CSI, where you could have GB: Dallas, GB: SanDiego, GB:PHOENIX (yes!), GB: London, GB: Tokyo, GB: WHEREVER!!! (I think a cool, creepy GB series set in southern Louisiana around the swamps would be SWEET. One of the guys on their team is an old guy who talks like a cajun and doesn’t actually bust, but knows EVERYTHING about the local legends, like a walking Tobin’s Spirit Guide for their team…and they have an Ecto-air boat [haha j/k!])