Here's my word of advice in regards to trying to ride off of trends and "The Next Big Thing": DON'T
Just draw what you want to draw. Chasing trends will just make you seem shallow and lock you into a cycle of never quite being "on it" and will probably just end up making you miserable in the long run.
I remember when I was working on DRAGOONS/DRGN, I tried to emulate a lot of stuff in webcomics that were popular at the time (especially one comic in particular my friend was doing.) and it just made me really unhappy because it didn't quite feel like it was 1005 "Me" if that makes sense. So i ended up scrapping it early on to work on something I wanted to work on, trends and popularity be darned. (That's a lesson I've finally learned as I work on the third reboot of my comic this year.)
As for fan art: Just draw what you want to draw and people will come to you if you like your art. I draw fan art as a break and I just draw whatever characters looked cool and resonated with me at the time. (I recently drew some fan art of Gaomon from Digimon: Data Squad. Nobody ever really talks about Data Squad. Heck, I've never even really watched that show outside of a few bits and pieces here and there. Gaomon just looked really cool to me.)
So what it al comes down to is this: Forget following what's "Trendy" at the moment and just do what you like to do. It might not get you the big numbers you want, but it will make you happy and more fulfilling in the long run. Plus, it'll make you seem more timeless if you just do your thing instead of always trying to cash in on the "flavor of the week."
So basically, stop being in it only for the big numbers like it seems like you've been doing recently, and just do what makes you the happiest in regards to your art and creative pursuits. Aim for that goal first, and you'll be a success every time.
Thank you for coming to my TED Talk. Good night everybody.