In this weeks Legends and Lore article Mearls writes how the cosmology for the D&D Next will look like. Most importantly when it comes to the outer planes, they are returning Planescape ...
http://www.wizards.com/DnD/Article.aspx?x=dnd/4ll/20130701
Do you agree with him, or there are better ways to do this?
I'm very happy they've come to realize that Planescape/Great Wheel should be the default assumption of the D&D Cosmology.
I skeptical about the Negative Energy border plane being called Ravenloft, that's a case where 4e's Shadowfell ends up being a better usage of the term. I'm not big on Ravenloft being the border plane, because I liked the campaign setting itself where Ravenloft was very clearly a demiplane.
As Elemental Chaos was invented as some catch-all place for all the Elemental planes, Limbo and the Abyss back in 4e. Now that it's the "Outside of creation" (yes I know the Far Realm is also another outside) it needs to stand on it's own, as we have that plane and Limbo and the separate Elemental planes.
I very much agree on the points about Spelljammer too. One problem with that setting was the location of the default homebase the Rock of Bral, which I always felt needed to be in it's own crystal sphere, and "DM insert into FR, GH and DL spheres". And many point out that the best SJ product was the Astromundi Cluster, because it was some place where SJ was truly on its own.