As a professional writer, it always pays to keep an eye on the industry. No one wants to write a book that they then have to shelve simply because it’s a played-out trend. But, as others have said over and over again, you should never try to write “on trend”. I personally believe that means you should not fail to write “off trend”, either: you shouldn’t decide not to write a book that you really want to, just because you’re afraid it won’t sell.
For one thing, you never truly have shelve a book if you don’t want to. Some things will always be in fashion, and other things come back into fashion again. It’s like when my 23-year-old boyfriend put on Abbey Road, then got miffed when I sang along with all the songs. He apparently thought The Beatles were some great band he’d rediscovered, not knowing that they’d never been un-discovered. Or it’s like when his 19-year-old best friend asked me, “Have you ever heard of this awesome band System of a Down???” Psh, step aside, little man. I was howling along with those fools when you were teething, but I’m glad they’re cool again.
If it doesn’t turn out that your genre is a trend that’s here to stay, and you don’t want to wait until it comes back into fashion (as it undoubtedly will one day), self-publishing and indie publishers are viable options. There is absolutely no shame in either, nor will you ruin your chances of hooking an agent with future books by taking that route.
Let’s look at how a trend generally happens (I’ll use genre trends as an example): someone writes a book that becomes really popular. Agents who really liked the book are excited to sign authors who write similar ones, and publishers snap them up, because readers are voracious locusts who will feast unrelentingly on that fresh crop of books until the stores and libraries are barren dust bowls.
Later, though, agents get tired of seeing query after query for the same darn thing (because writers also loved the book that started this whole mess, too…or because they unfortunately think deliberately writing “on trend” is a good idea). Publishers also eventually stop buying books in that trend, because the market is saturated. It isn’t because readers have stopped loving books in that genre, it’s just that there is now such a thriving crop of them that the locusts will have a hard time devouring them all in their lifetimes, and so it’s hard for one book to stand out and make money. That’s why, like I said above, self-publishing and indie-publishing are viable options for off-trend books: those books still have an audience, and you (or your indie publisher, who might specialize in that niche audience) can find them.
HOWEVER, just because you’re writing in a supposedly played-out trend doesn’t mean you’ll never find an agent or a big publishing deal, even before the trend comes back around. Say you write a spectacular vampire romance. You aren’t trying to copy Twilight, you just have this really powerful story that you HAVE to write, in your own new and different way. If that’s the case, you could probably find an agent that sees that greatness, and realizes they can pitch it with a spin that appeals to publishers.
With regard to trends besides genre trends, specifically the “first person, present tense fatigue” that I spoke about in my earlier piece…I’m sorry, but I find this “trend” hilarious in a way. I was wondering if this sort of thing would happen, since a while back a lot of agents were lamenting that they wanted to see more YA written in first person present. The thing about tenses and points of view is that, unlike genres, there are very few of them. As long as you’re choosing the ones that are best for your characters and story, and aren’t just writing or failing to write it in a certain way because you’re worried about trends, a reasonable agent won’t turn you down just because of that. Unless, perhaps, if it’s second person or future tense (though you could find the right agent for these if you are skillful).
Writing is indeed a business, but it is first and foremost an art. You should write the books that are in your heart, and write them the way you want, whether it’s on trend or not. There will always be more books for you to write in the future, and you will never lose out by telling the stories you hold dear now.