SPECTRE666 said:
This is one of the possibilities I saw (in general--my Realmslore is limited) when they revealed yesterday that every world has its own set of astral dominions--arguably 'the best of both worlds', allowing most of the D&D worlds to connect with the core cosmology while retaining their individuality.
In my experience, it's always been the Outer Planes/divine realms that were problematic in the non-Wheel settings (Dragonlance, later FR, etc.). Nearly everyone else either uses the Inner Planes as they stand and/or ignores them; very rarely are they replaced. Dark Sun may be the exception, but then, Dark Sun is
always the exception.

Everyone has the Astral Plane/Sea or a close analogue to it. In the new cosmology, the Feywild and Shadowfell are Prime-connected and could easily be modified or ignored for each setting, the elemental planes were fairly constant and can be replaced by the Elemental Tempest (previous planar scholars only explored 'stable regions' that they divided into individual planes, not understanding the greater whole), and the divine realms can remain world-specific. The Abyss might be the only problem, but even that could work with a general 'out there, there be monsters'.
Some thoughts on reconciling older cosmologies with the new cosmology.
1. In FR, the Fugue Plain could be identified with or recast as the Shadowfell. This could have been a stealth correction, but with the Spellplague and cosmic chaos, perhaps the deities decide to move it 'closer' to the Prime to keep souls from getting lost.
2. In DL, the term 'The Abyss' applies to Takhisis' divine realm (
not the Nine Hells). What the core cosmology refers to as the Abyss, Krynnish scholars call the Void of Chaos.