So if you lean even harder into 4e's setting assumptions than 4e dared, you can easily wind up with a system where all power sources are tied to a plane and "martial" (aka "no power source") isn't appropriate for player characters.
What do our classes end up looking like if we drop the arcane and martial sources and make elemental, fey*, and shadow core?
No more generic fighter, rogue, wizard, or sorcerer. Instead we get things like
- A xianxia-inspired warrior who uses psionics to boost their martial prowess a la this trailer (for a sadly never-produced show):
- Basically the Mindthief from Gloomhaven
- A Shadowmage, who commands the power of darkness (nethermancy and necromancy)
- An Elementalist base class
For reference, the existing power/plane correlations (besides the obvious ones) are:
Astral: Divine
Far Realm: Psionic
Natural world: Primal
*You could still call it arcane, I suppose, but it would explicitly be the magic of the Feywild rather than a catch-all.
What do our classes end up looking like if we drop the arcane and martial sources and make elemental, fey*, and shadow core?
No more generic fighter, rogue, wizard, or sorcerer. Instead we get things like
- A xianxia-inspired warrior who uses psionics to boost their martial prowess a la this trailer (for a sadly never-produced show):
- Basically the Mindthief from Gloomhaven
- A Shadowmage, who commands the power of darkness (nethermancy and necromancy)
- An Elementalist base class
For reference, the existing power/plane correlations (besides the obvious ones) are:
Astral: Divine
Far Realm: Psionic
Natural world: Primal
*You could still call it arcane, I suppose, but it would explicitly be the magic of the Feywild rather than a catch-all.