One thing I (usually) like about Dungeons & Dragons is that, unlike a lot of other role-playing games, there is no default world (though I guess 3rd Edition kind of implied Greyhawk). Sure, races have their assumed traits, and you can pick up a prefabbed campaign setting, but there are rules and guidelines to help you create your own world, going into as much detail as you need or want.
That being the case, why is it that there needs to be a default cosmology? Planescape featured the Great Wheel, which 3rd Edition kept (though Forgotten Realms had some kind of tree thing going on), Eberron had the outer planes orbiting the prime material, Dark Sun had at least a handful of other planes, and 4th Edition gave us the World Axis.
In other words there have already been a number of divergent, official cosmologies, so why try to condense various degrees of the popular models into a single, default one that tries to use “as much prior material as possible”? Though I prefer 4th Edition’s World Axis and whatever you would call Eberron’s 3rd Edition iteration to the Great Wheel of editions past (despite being a Planescape fan), why not have them all as potential examples for DM’s on the go?
It is all well and good that they are trying really hard to please everyone with this, but they do not need to. 3rd Edition’s Manual of the Planes took the toolkit approach, by telling you what a plane is, what each planar trait—like gravity, time, shape, size, etc—means, how the planes interact with each other, how to get from plane to plane, the Great Wheel as an example cosmology, and how to build your own. Oddly it was after that point that it went into thorough detail on each “classic” plane, giving you the traits, inhabitants, other features, and even telling you the repercussions of removing the plane (if any).
This book already exists. Just clean it up, cram several examples in there (Great Wheel, World Axis, and whatever else you want), and you are good to go. This way everyone gets what they want; people who liked previous cosmological models can use those, and people who want to make their own have the tools on hand to do so. To me this sounds more conducive to the idea of making Next the edition for everyone.
That being said I dig the idea of the border elemental planes. The concept sounds similar to Exalted’s elemental poles and Wyld, (which is fine because Exalted has a lot of awesome story content), or like a mix of 4th Edition’s Elemental Chaos and the Feywild and Shadowfell mirror planes. Either way both takes are more accessible locations for actual adventuring, so that it also a plus.
If you go beyond that you hit the deep elemental planes, which I guess were more like how they were portrayed in 2nd and 3rd Edition (maybe 1st, I do not know) in that they are pure elemental energy. So fire for fire, water for water, etc, which I really dislike because it makes them less useful for adventuring. I am guessing they will include pockets of other elements, so players may not have to rely on high-level magic to get around, but unless they do something to make them interesting I will probably just remove them.
After that you get the elemental chaos, which is briefly mentioned as “a region of pure, fundamental elemental energy”. I am not exactly sure what that means, but unlike 4th Edition’s Elemental Chaos—which you could actually go to and survive without powerful magic—it actually sounds worse than the individual classic elemental planes. As with deep elemental planes if it takes high-level magic to get there and survive then this is also getting the axe in my campaigns.
The bit about Spelljammer confuses me. Are people really going to get upset because a campaign setting they may not even own mentions one that they might be using? Magical pirate ships in space sound like they would probably be fairly easy to ignore, what with them being in fantasy space and all. Actually I never had much interest in Spelljammer, but from what I have seen I would probably prefer my own setting.
Awful Good Games 
