WotC has made mention of their upcoming concepts for new releases (as seen in this article from EnWorld). Essentially new releases are tied into a "storyline". The upcoming storyline is Elemental Evil which features the Adventurer's Handbook (a book of player options centered around the storyline) and 2 Adventures (of which the first will be Princes of the Apocalypse).
While I like the idea of a central story arc to drive products, I am not happy that the Adventurer's Handbook will be so closely tied into the storyline/adventures. Basically, the Adventurer's Handbook is a splatbook for playing characters where the the characters have backgrounds in the Elemental Planes or options for characters interacting with those planes. As a DM I am looking for splatbooks that are more generalized. This book seems as if it will be too closely tied to the adventures.
Another example given was that of psionics. Any future book on psionics will be tied into whatever adventures/storyline is ongoing at the time. In my "psionics rulebook", I don't want it cluttered up with background information on a setting I may not be using. All I want are rules for psionics.
We'll see how the books are actually written but I expect a lot of useless information in my splatbooks.