I thought I'd share a few thoughts that came out of the New York SCBWI booksellers panel. Because of the emphasis on Common Core Standards, we may see a resurgence of picture books for school age children. Specifically, booksellers are expecting more nonfiction, narrative nonfiction, fiction with a nonfiction link (based on a true story, for example, perhaps with an author's note or supplemental web material), and fiction with nonfiction back matter (bibliography, glossary etc.).
Also, we may start seeing more interest in folktales and fairy tales! I'm guessing that this will be mainly for traditional tales, especially from nonwhite cultures, with back matter on history/culture, to tie into the "informational" text focus. That last sentence is just my interpretation, though.
I doubt this means that we've seen the last of "character driven picture books with series potential" like Fancy Nancy or the Pigeon, which have been dominating picture book sales. But there may be room for more variety in the near future. If you are writing fiction, think about how you might tie into common core standards with an educational aspect. If you are an illustrator, note that the ability to draw a realistic images may be a benefit.