I like the idea on the surface, what little has been said about it. As jgsugden said, kinda hard to make an informed opinion.
One thought that occurs immediately is that the system may benefit from moving some spells off the core-4 spell lists and directly onto classes. Like all warlocks get e-blast and hex, all rangers get hunter's mark. Basically, each magic using class has an expanded spell list exclusive to them, but it's only a small handful of spells, similar in scope to the existing Domain/Circle/Oath spells for archetypes.
If they were going to do it, I would probably base it on the idea that magic comes from different planes: so primal (material), transitory (feywild, shadowfell, ethereal), elemental, spiritual (outer planes), and mental (astral, far realm) lists. It seems like that could be a good set up for subclasses--every caster class gets a main list and their subclasses determine the secondary list.
Druid: primary is primal, subclasses for transitory (like those fey) and elemental
Cleric: primary is spiritual, nature gets primal, trickery gets transitory, community gets mental, dwarves get elemental
etc.
I like this. Very flavorful!
I might prefer it if each plane got it's own list. Shadowfell magic could easily be separate from Feywild magic, although giving each outer plane a distinct list might be a hassle (although they would make a neat replacement for domain spells).
Ooh, and on top of that, the "basic" spell list could be the Weave.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.