Apparently they are considering it

Do not want. Nothing about her makes me excited in the least for this, and while some would suggest her role on Dollhouse has given her experience playing the role of a sexy female that can kick some ass, I say that role has demonstrated precisely why she SHOULDN'T EVER play such a role and expect to be taken seriously. She's also not masterful enough for me to care about any joke she delivers alongside Bill Murray.

Okay okay, then let's throw out the conversation on Dushku and instead concentrate on the idea of a new generation of Ghostbusters. I mean, if this movie gets green lit, it could work kind of like Star Trek: Generations, with the old passing the torch to the new. Are we willing to accept new Ghostbusters, or is the magical combination of those guys the only way Ghostbusters can work?

Everybody is asking questions that are RELATED to the big one, but nobody seems to be asking THE most important question - "Will adding Ghostbusters make it better or worse?" I don't care if they're male or female, the 'old generation' (Moranis) or 'new'. If it's a new member of the team, then there needs to be a damn good reason for it in the story, as well as an appreciable increase in the entertainment value.

Honestly, I think Rogen is a fantastic choice. He's funny, a decent actor, and respectable enough in my mind to continue the story without offending anyone with his screen time outright. Remember to separate Rogen as an actor from the ridiculous characters he's player. His delivery and range would work very well with a property like this. All I'm hoping is that the new female GBs aren't just going to be hyped up tomboys that are an excuse for intracompany romance.

As for the whole passing of the torch deal, I agree with Sean; I really hope they do something meaningful with the old cast instead of just having them show up, say the equivalent of YER DOIN IT RONG LEME SHOW U a few times and then quietly fade away. This may be a weird parallel, but I'd like to see it done like Mythbusters. Everyone's cool, everyone sort of does their own thing, but at the end of the day they're a team. We're all probably overthinking this, and I DON'T want this to be a movie for the fans, I want it to be a good goddamn movie. If that even meant leaving out the old cast entirely, I'd go that route.

Actually, I could see the originals retired after Ghostbusters 2, then some vauge curse came around 15 years later. They decide to reopen Ghostbusters Inc and recruit the new generation. The old and new team up to fight the ghosts, and at the end the old work only at HQ (providing jobs, technology, etc), while the young go out and fight the ghosts. It would allow the old to make cameos in any future Ghostbusting while still letting a new generation shine.

io9 posted an interesting idea from BLDG BLOG's Geoff Manaugh. Here's the basic pitch, copied wholesale:

It's 1997. NYNEX is on the verge of being purchased by Bell Atlantic, after which point it will be dissolved in all but name.
But all hell starts breaking loose. Pay phones ring for no reason, and they don't stop. Dead relatives call their families in the middle of the night. People, horrifically, even call themselves – but it's the person they used to be, phoning out of the blue, warning them about future misdirection.
Every once in a while, though, something genuinely bad happens: someone answers the phone... and they go a little crazy.
Thing is – spoiler alert – halfway through the film, the Ghostbusters realize that NYNEX isn't a phone system at all: it's the embedded nervous system of an angel – a fallen angel – and all those phone calls and dial-up modems in college dorm rooms and public pay phones are actually connected into the fiber-optic anatomy of a vast, ethereal organism that preceded the architectural build-up of Manhattan.
Manhattan came afterwards, that is: NYNEX was here first.
It's worth recalling, in fact, that NYNEX – at least according to Wikipedia – actually stood for New York/New England, "with the X representing the unknown future (or 'the uneXpected')." It's like Malcolm X's telephonically inclined, wiry cousin.
So the phone system of Manhattan – all those voices! all those connections! leading one life to another – starts to act up, provoked by its dissolution into Bell Atlantic... and the Ghostbusters are called in to fix it.
Fixing it involves rapid drives from telephone substation to telephone substation, from library to library, all while Dan Ackroyd's character keeps receiving phone calls about a family crisis... his ex-wife is calling... his dad is calling... they're urging him to stop this whole, crazy Ghostbusters business... He starts acting funny. The voices on the phone say strange things. They call at strange hours. He feels kinship with public pay phones; they sometimes ring as he walks past. He tries to call his family back – but they're not answering.
Harold Ramis starts to suspect something.
In the background there are shadowy figures called out to fix transmission lines – but they are actually wiring something up... something big...
The whole movie then leads up to the granddaddy of them all: an electromagnetic confrontation inside the windowless, Brutalist telephone switching tower at 33 Thomas Street (rumored haunt of the ghost of Aleister Crowley).

I like the premise, but it's not a filmable movie as-is. Well, OK, let me qualify that: it's not Ghostbusters as-is. It still needs an entire subplot allowing a little more focus on the Ghostbusters themselves, instead of these random phone-callers. Also: that explanation of the X in NYNEX meaning "the undefined future" sounds dubious.

That....that sounds like a terrible idea! Well, I mean it sounds like a terrible idea. Well, it sounds like a terrible idea of a Ghostbusters movie. I think I might like it as just a supernatural thriller. But as you said, there's too much of other characters and not enough Ghostbusters Ghostbusting.