While it's already been covered, I will say not to focus on what's popular. It's a good way of burning out. Write what you love or would like to read. That way when it's done, you're excited about it instead of feeling like you're finally free of it.
I can't stress how true this actually is. I almost burned out with my second novel because I introduced an outside element that I didn't really enjoy that I thought I would like. Writing it was amazing for the first 3-5 days, but as time went on it actually made me less happy with the story.
I digress, though. I know that a bunch of the publishers I eye for submissions would be very happy with an epic fantasy erotica piece. A good plot only makes the erotic scenes that much more delicious, IMHO.