It's kinda cute how the studio had such faith in this movie they believed it would earn enough to justify a sequel. I mean, it might, but they planned around the idea that it would.
Thing is, it
can't. It's in the same hole as Superman Returns, in that it's spent so much time in development hell, so many scripts, and a high budget on top of all that, it's unlikely to earn much profit. So the sequel's justification to Sony would be that the first one makes the money back and the sequels reap the profit on the original's popularity.
Which means that if the trailers hadn't received such harsh backlash, even if the movie tanked we could still have seen sequels. Now things are up in the air and already Sony's American Creative Market Blah Blah Big-Earning Title Guy has "decided to step down" AKA told to resign or be fired. If this movie doesn't do well, they may can the whole project like Fox did with Fantastic Four 2015.
Also I've read that Melissa McCarthy was paid $25 million to be in this. -_- Oh yeah, that's money well spent. There are other plot elements I haven't gotten into from that leak that really make me not want to see this, like shit about a ghost mob family that gets resurrected, or how McCarthy's character uploads a video of Wiig getting slimed onto Youtube, killing her chances at a job she wanted and leaving her no choice but to enter the ghost hunting venture with the others. Oh, the outburst of laughter and swarm of chuckles to be had. Now we get the quality writing as seen in recent films like Jem.