2. Ghostbusters
With Ghostbusters 3 constantly fluctuating in and out of development hell, there really isn't any guarantee that it will ever see the light of day, no matter what Dan Ayrkroyd says. If it takes much longer for the movie to get off the ground, the principle cast is eventually going to be too old. Having said all of that, no one wants to let the franchise go for good. Once we pass the window of the original cast being available to star, a remake may become the only recourse for getting the Ghostbusters back onto the big screen. Whether they go for a relatively straight retelling of the original story, or try their hand at some sort of 'next generation' type thing, it's a safe bet that we will see a new incarnation of the team at some point in our lifetime.