It is a safe bet that the next campaign from Paizo will not feature a major outsider enemy. It will probably have a far more terrestrial focus, and most likely won't jump around as much as the Age of Worms or Savage Tide.
My original plan for the post-Age of Worms Adventure Path was to be a massive war between the elven nation of Celene and the orc hordes of the Pomarj, again with the focus on the most basic of D&D concepts (orc/elf war) and lots of political intrigue in the elven court. Prince Melf was to be a major player, with another cameo from Celeste and probably Manzorian/Tenser.
Ultimately we decided to go another direction, but not without spending a lot of time thinking about using a war as a background and framework for a campaign. We haven't seriously started discussing the next campaign, but something with a "hot" war going on in the background is a strong contender.