Well, I already suggested this, and after a heated discussion, the idea was successfully discarded – there are many problems: where will we get so many skills for magic, and there aren't that many spells to distribute them among seven skills from four – although it would be interesting, we could also use racial skills and make them available not for one Faction, but for several (for example, rework Unstoppable Magic into Fire Magic and make it available to Dwarves, Demons, Warlocks, Mages, and Humans).

But this is tedious, and the question is also how this will affect not Multiplayer, but single-player maps and campaigns with scripted events, etc. – I don't think it's worth going to extremes, unless we do something similar to Heroes 3 and create 4 schools: Water, Fire, Earth, Air. But specifically, Light and Darkness, as schools of magic, and not something amorphous, are very characteristic of the Ashan universe...

And so, what was I talking about...
:D
How will we distribute the schools?

Darkness-Chaos:-----------Inferno---------Dungeon-----
Light-Summoning:----------Humans---------Sylvan--
Chaos-Summoning:--------Academy---------------------
Darkness-Summoning---------Necropolis--------------------
Chaos-Light:--------Fortress-----------------

For Dwarves, replace Summoning on the path to Supreme Unit with Machinery, and the problem is solved.