The article itself is interesting for what it says of the design of the 4e cosmos.
It suggests that above the Prime there is the Astral Sea, in which can be found the domains of various deities - including Asmodius' Nine Hells domain.
On the other hand, beneath the Prime is the Elemental Tempest, within which can be found the Abyss wherein demons and perhaps even Tharizdun are contained.
What is interesting most to me in this is that the Elemental Tempest reminds me rather strongly of the 2e Ethereal - the plane between the Prime and the Elemental Planes. I think that perhaps the elements will - instead of distinct planes - be numerous domain-like pockets or demi-planes within the stated Elemental Tempest. Some may be of a single element, while others may be of several elements. It is an interesting design decision. So those that prefer the elemental planes as they currently are will still have (demi-?) planes within the Elemental Tempest that are of a single element - if that is where they wish to adventure, while others will have elemental (demi-?) planes of multiple elements - perhaps even all of them. The latter result may even seem at first glance by visitors to be odd other Primes. Perhaps Primes 'grow' from such seed-planes where all the elements have by chance come together in the Elemental Tempest.
I also find it interesting that Devils are evil-tainted Celestials, while Demons are evil-tainted Elementals. That makes for a rather profound difference, actually. I wonder where it will eventually lead . . . .
The fact that Demons are former elementals - and as such care little about gaining / converting souls (and, in fact, likely seek the destruction of souls, meaning that any souls drawn towards the Abyss are unlikely to - or at least rarely - become demons) also brings about some rather notable (perhaps even extreme) differences and changes to the perception, arrangement, and use of the Abyss in the cosmology.
In addition to the divine realms pocketed like (demi-?)planes amongst the astral sea, I wonder what other planes may exist there. I also wonder what other (demi-?)planes may exist in the Elemental Tempest.
Of course, all this does ring the death knell of the Great Wheel, as it seems that it has finally, completely, been dropped from consideration. Hmm, I wonder if a Rule of Three might still exist. If so, perhaps in addition to the Astral Sea above and the Elemental Tempest below, there will be another plane beside the Prime (Shadow?).
I wonder if - like the succubus - all the schemer type demons might be moved over into the devil camp? Grazzt may end up being a devil in the next edition, for example.