Some existing fandoms are also going to get a boost from successful sequels or brand extensions. They include:
Not only is Star Wars: The Force Awakens likely the biggest movie since Gone With The Wind, but
Rey, Finn, Poe, and Kylo Ren all appeal to different types of cosplayers, and there's already a lot of interest in Kylo Ren's three-pronged lightsaber. Meanwhile, the original trilogy characters are cool all over again, and the new Storm Troopers are just different enough to force the various 501st clubs to invest in the new suits.
Harry Potter fandom is one of the most rabid and loyal out there, and it's been a while since they've had anything new to obsess over. So the original promotional stills for Fantastic Beasts and Where to Find Them led to wizard-loving squees all over the internet. Fandom adoration aside, the colors and textures on Newt Scamander's costume are also impressive for cosplay aficionados, even if they're not hardcore into Potter.
Deadpool is already an extremely popular cosplay, and with some great trailers out for the Deadpool movie, I can't see him going away. But I think Deadpool is going to step out of being a joke character and become a leading man, albeit a comic one... pardon the pun. Equally importantly, the movie interpretation of the suit is legitimately cool looking, and it can be made by augmenting and painting leather gear you can buy off the rack. All signs point to this being an even more popular cosplay this year.
The Suicide Squad movie versions of the Joker and Harley Quinn are already all over the place, and I think that no matter how bad the movie is, there will be a diehard core of cosplaying fans. Harley Quinn makes people lose their minds no matter what she's in, and once some of the other characters become known to film audiences, expect to see them popping up at conventions.
Sometimes you just want a costume where it doesn't matter if you're bloated, it doesn't matter if you have perfect makeup, and it doesn't matter if you shave your legs. The upcoming Ghostbuster's movie is perfect inspiration for this sort of costume. And since there's already a robust network of Ghostbusters cosplay clubs out there, expect them to fly their colors when the film is out in July.
The Black Face Sock Daredevil
I didn't know what else to call Matt Murdock's original DIY outfit before he gets the red Daredevil suit, but expect to see more of them because they're fairly easy to put together and, again, they obscure the cosplayer's face. Further increasing the appeal of this cosplay is that you don't have to be in the gym every day to pull it off - Matt Murdock has a leaner build.