On Chasing Trends.... And why you should just write the book you want to write...

Everyone in publishing likes to talk about trends, it seems. Its one of those things that comes up constantly in tweet chats, conferences, phone calls, PW articles, etc.
 
What's hot? What's not?  How can I capitalize on that?

Here's the problem:
A) The next big thing never looks like the last big thing, so you'll never be able to predict it
and
B) As a writer, by the time you hear about a trend, its too late to jump on the bandwagon if its not already written.

Case in point: About the time PERCY ...