In the days after Harold Ramis' passing, many wondered what that meant for the Ghostbusters 3 project that had been developing for several years. Ramis was not only one of the stars of the previous films, he was also the co-writer. He and Ghostbusters director Ivan Reitman had been working on Ghostbusters 3 between other projects, and without him it seemed like the project might never happen.

This doesn't seem to be the case. Sony (SONY -0.33%) recently announced that production on Ghostbusters 3 would begin early next year.

Who you gonna' call?
Rumors have persisted for a while that Ghostbusters 3 would center around a new group of Ghostbusters. The original cast would largely just be "passing the torch" as is common with soft reboots these days. Failing a hard reboot, it seems unlikely that anything else could be done now.

The question is, who exactly will still be around to pass that torch? Dan Aykroyd's Dr. Ray Stantz is the most likely candidate, since Aykroyd is co-producing the new film with Reitman (who won't be taking directing duties this time). Ernie Hudson, who played Winston Zeddemore in the first two films, expressed interest in the past but recently stated that "there can't be another 'Ghostbusters' without Harold." This seems to indicate that he won't be returning for the new film.

Then, of course, there's Bill Murray. There have been a number of rumors concerning his involvement; some say he's in, some say he's out, and some say he absolutely hated the script. Reitman attempted to put some of this to rest recently, saying that Murray had at best read 15 or 20 pages of the script and simply wasn't interested in a leading man role anymore.

When you add in other missing cast members like Rick Moranis (who retired from acting in 1997 to raise his children), the story of Ghostbusters 3 will have to focus on an almost entirely new cast with perhaps Ray as a mentor. That's not necessarily going to appeal to all "Ghostbusters" fans.

What's essential for a 'Ghostbusters' film?
When considering Ghostbusters 3, it's important to think about whether the cast was vital to the success of the previous "Ghostbusters" films. If the cast carried the films then there's little hope for a third movie; if they were just one component then things might still turn out well.

Though it might seem hard to picture Ghostbusters without its iconic cast, most of the roles weren't actually created with those actors in mind. Bill Murray's Peter Venkman was originally written for John Belushi, while supporting roles were written with John Candy and Eddie Murphy in mind. Unfortunately, Belushi died before the film was developed and neither Candy nor Murphy committed to the project. Changes were made to tailor the parts to a new cast, and now it's hard to imagine what the film would have been like with its original intended cast.

While the cast that eventually filmed Ghostbusters made the film their own, the fact that they weren't originally intended for the roles provides a glimmer of hope for Ghostbusters 3. Two of the original writers (Aykroyd and Reitman) are still involved with the project, so it's possible that the script could be tailored to account for the loss of Ramis without losing the feel of the original films.

Why now?
While the timing seems odd in light of Ramis' death, it's likely that Sony was close to giving Ghostbusters 3 the greenlight regardless. Though there are similar projects that have languished in development hell for years -- such as the third "Bill and Ted" movie -- statements from Aykroyd and others involved have been hinting at a production deal being close for several months.

For Sony, this could be an opportunity not only to potentially relaunch the franchise but also to cash in on the nostalgia trend. With other franchise restarts such as Jurassic World from Comcast's (CMCSA -5.82%) Universal Pictures finally being made after a decade-long struggle and '80s nostalgia being in full swing, the time seems right for Sony to resurrect the "Ghostbusters" franchise after a 25-year lull.

The original Ghostbusters earned $291.6 million worldwide on a budget of only $30 million. The studio put pressure on the producers to make a sequel, and while financially successful, Ghostbusters II only earned $215.3 on a budget of $37 million. Despite both films having phenomenal earnings for their time, the box office drop and mixed reviews of the second film obviously played a part in it taking this long for a third installment to move forward.

Is 'Ghostbusters 3' a good idea?
The ultimate question in determining the movie's fate is how much Sony thinks it could pull at the box office.

Someone who saw the original in theaters in 1984 as a teenager is in his early 40s now, and might feel a strong pull to relive that nostalgia, while also sharing it with his kids. If the movie is decent, it's fair to assume it could at least match the second film's box office. Adjusted for inflation, that would have it topping $400 million. If the studio can keep the budget between $70 million and $100 million, that's a nice return. 

All told, given the rising popularity of older franchises, this is likely too much potential for Sony to pass up -- after all, if there's a "Jem and the Holograms" movie being made, why not "Ghostbusters 3"?

That said, Ghostbusters 3 could still flop. With almost none of the original cast returning, it will be much harder to play on nostalgia for the old films. Sony will need to appeal to both fans of the original and to younger audiences who aren't attached to the original cast.

If the film performs well when it's released, expect a new franchise to launch that focuses largely on the new cast. If it doesn't meet expectations, though, then the "Ghostbusters" franchise might finally give up the ghost for good.