That's right. Seven!
I was just listening to "The bells of the Seven Hells", thinking about how it's usually 9 of them, when it hit me: Pathfinder really should have seven hells - one for each sin.
If it's about punishment, they could be the opposite of what the denizens onse wanted: The Hell of Sloth is the hardest forced labour camp existence, in the Hell of Pride, the pitiful petitioners are ridiculed for all eternity, and so on.
It's a no-brainer, really!
Thematically, its actually a damn good idea. Certainly not what I thought I would be saying as I first clicked the posting.
It makes a great deal of sense, though I have no idea what kind of actual cosmology they have in mind for Golarion. It all depends on how it interacts with the world.
I read something about the Ethereal Plane in the write-up of Desna, so that appears to be in (though you can never be too sure, of course).
Let's hope that they do something unique. No Wheels, Trees, or whatever Wizards seems to try to force upon us.
An idea I had a while ago (when I was idly tinkering with my own campaign world) was this:
All of Creation is first divided into three cosmoses: The Material Cosmos (where mortals frolick around), the Elemental Cosmos (where the physical building blocks of creation are stored) and the "Spiritual Cosmos" (where the psychic, mental, intellectual, ideal building blocks of creation originate from. I didn't settle on any single name for that part. It could also be Ephemeral, Mystic, or something like that).
The Elemental Cosmos is one infinite space where the primary elmenental planes are at the edges, along the equator - fire, water, earth, air - and at the poles life and death. Between are the paraelemental planes, positive elemental planes and netagive elemental planes. At the centre would be nature, and force, time and space would be all over.
(I intented to use Elements of Magic for the campaign, and that has a lot more elements than just the usual 4, and all of them have elemental spells and resistances, though there are always some friendly and unfriendly ones that interact).
The Spiritual Cosmos would be similar, though it wouldn't consist of elements, but concepts and their interplay. Good, evil, law, chaos, and many others would be found on certain "coordinates"
The Material Cosmos, finally, would be comprised of a solar system: At the centre, there's the Sun, giver of live and light. At the very edge, a Dark Star/Black Hole, a place of death and darkness. Around that, in a shared orbit, the 4 planets that make up the normal place you adventure on: Earth as well as Fire, Water and Air. On each, the prime elemental it is named after dominates (though it is not exclusive) (each creature would get minor abilities depending on where it was born). Since countless portals existed all over the Four Planets, that wouldn't be a problem, and interplanetary metropolises that exist on more than one planet at once, would exist.
The other planets in the system would be the home of, and named after, the deities that make up the pantheon. So Mars would be the Home of Mars. Lesser deities (something like demigods and other powerful beings) would instead have moons orbiting their masters' planets. The deities would hold open connections to the spiritual planes that match their portfolio and outlook.
Travel on and between the Four Planets would be accomplished via portals, mostly (or just going there on foot or wagon, in case of intraplanetary travel), or via plane shift magic (which would be somewhat easier to accomplish between the Four Planets than to other places, and have lesser spell versions). The deities' homes, on the other hand, could only be reached by their express permission, which could then be done via plane shift or portals (which could exist already or be created on the spot by the gods).
Travel to other cosmoses would effectively be like plane shifting, but harder, since it's "cosmos shifting". But in certain places, the boundries are thinner - the bottom of a deep sea would make it easer to get to the Plane of Water, or a place of great slaughter would lead to spiritual planes like Evil, Chaos, or War.
If this doesn't sound like complete rubbish and anyone is in need of a cosmology, feel free to use this one, or parts of this one.
You forgot the most important Cosmos of all, the Customer Service Cosmos!
I'm just gonna chime in that I think you've got a really good idea there and I may keep it regardless of what Paizo has planned.
Cheers!