Jeff Carlsen
Adventurer
Mike Mearls has been tweeting a bit about the elemental planes. The basic gist is that they are working on elemental border planes that are like the material plane where one element dominates. He says that all the details haven't been nailed down, but they want to add to existing cosmology without altering it significantly.
I imagine these to be a bit like elemental versions of the Feywild and Shadowfell. This allows the two best parts of the World Axis to be melded into the Great Wheel. In essence, you have the true positive, negative, and elemental planes, which are very unfriendly to human life, and then you have the border planes. The Feywild and Shadowfell are clearly related to the positive and negative energy planes. Elemental border planes flow naturally from that and have the potential to be very interesting adventuring locations.
I imagine these to be a bit like elemental versions of the Feywild and Shadowfell. This allows the two best parts of the World Axis to be melded into the Great Wheel. In essence, you have the true positive, negative, and elemental planes, which are very unfriendly to human life, and then you have the border planes. The Feywild and Shadowfell are clearly related to the positive and negative energy planes. Elemental border planes flow naturally from that and have the potential to be very interesting adventuring locations.