It’s still the dream of most authors to get an agent, have the agent sell their book to a big publisher, and have a bestselling book. The major publishers are still the only game in town when it comes to that dream. But you might want to think before you decide to play that game. There are potential pitfalls, and not just getting lots of rejections.
Trend Trouble: Right now in the SF/F genre "paranormal fantasy," usually featuring female leads, is the hot property. What if that’s not what you write? Unless your work shows promise of big sales, you are plain out of luck. You may find it hard to get an agent, much less get a contract with a big publisher.
This isn’t something new, either. Ten years ago fantasy with female leads would have been a tough sell. Twenty years ago any fantasy would have been the tough sell. Who knows; maybe in a few years paranormal fantasy will fade and steampunk will be the hot property?
This points to another problem with selling to the majors. What happens when the trend you’re a part of falls out of favor?
In the past the answer was "not much unless your sales dip below 10,000 copies." As long as you didn’t get below that number of copies sold you’d still have a contract. We’re in a much different enviornment now. The majors are owned by larger corporations with less of a tolerance for lower profits, much less losing money. What no one knows, until that shift in sub-genre hits, is how high that threshold number has risen. Which leads to...
The Sales Peak: The vast majority of genre novels being published today are parts of series. Since the phenomenon of the "novel series" took off about 30 years ago, it seems that every series hits a peak point. The peak is where interest in the series reaches its height. After that growth in sales is minimal, or sales start to shrink.
Again, in the past sales had to really plummet before an author was shown the door. Now the majors have those new owners. How many books past the peak will the publishers tolerate before cutting an author loose? Will they even wait past the peak? Where does that leave the author, who has invested years in their series, and might still have thousands of fans?
Deadline Drought: One other aspect of the series phenomenon is that bestselling series authors are now expected to come out with a new novel in their series about once a year. This sometimes results in the author producing a novel in the series that just isn’t as good as the ones before. The pressure of meeting the release deadline can lead to some sort of artistic compromise. As it happens, it can sometimes be at this point that the series hits the sales peak.
I’ve already mentioned how this might affect the author-publisher relationship. There’s also a creative dimension to this that authors often don’t consider. Can you stand being under pressure to write a new novel every year without fail for five, six, eight, ten years or more? Do you understand the sacrifices you might have to make to fufill your contract? Can you create on a deadline? Can you keep at it for years?
Everyone talks about getting the big book contract, the advance, and the ability to be a bestselling author. No one mentions any downsides, but they do exist. Consider them before looking for an agent or a major publisher. Several books in is no time to find out that you can't cope with them.