Just as a warning to all you other wannabe writers, get the books you want to write written as soon as you can.
Many more years ago than I wish to think about, the ideas that formed the bones of the current WIP all came together. I won't bore you all with the various Big Ideas™ (trademark of John Scalzi's Whatever), but my elevator pitch is "the Left-Behind romantic comedy for those of us that will be Left-Behind." Sounds like fun, doesn't it? Also, it's a great joke Christmas Tree. But I also shouldn't go into all the details about what's in there because I want to talk about timing.
Let's assume for the moment I can pull this writing feat off and this is going to be a killer book, the kind that the young kids in college ask each other, "Have you read this? You gotta read this" (yes, those dreams of being a Douglas Adams keep coming back no matter how many times reality wants to stake them down). If I had finished it in a relative time frame from when I had the entire story structure down, that would have been about 3 years ago. Let's say a year to get an agent and then two years for the publishing process, the book would probably be coming out soon.
Which would have been great given this summer's movie preoccupation with "End of the World" stories (including not a few "Biblical Rapture" movies on all sides of the issue). That book would have hit the market at a time of high-tide for interest. I can't tell you how much internal strife is going on with that thought right at the moment. Seriously kicking myself over it.
Right now my guess is if I can get it done, we're looking at another 5 years until it might be out (unless a miracle happens - I'm looking at you Powerball). Who knows what the public interest will be then.
So, if you have that killer idea, the one you're not seeing on the shelves right now, write that bugger as fast as you can. Because by the time it's out for sale, you'll never know what will be fashionable or riding the wave of public attention.
And in case you don't see the other part of this argument, write what you want to write about, not what you think the market wants (except for short stories, this is one of the differences between shorts and novels).
Get to writing.