I do like your idea but I personally hope they nix the Disciples of War/Magic and just make it a Disciples of Combat and then be able to mix classes easier that way. An idea I posted in another thread for a pet related class was:

Pet Class - all rounder, non-specific, weaker(or shorter duration charms)/"jug" pets/spirits(elementals)/etc
-Job1 stronger elements than class
--Job1a use of primals
-Job2 imbue an elemental giving you an aura/spells
--Job2a transform into a primal/humanoid race hybrid
-Job3 temporary charm pets
--Job3a permanently trap pets
-job4 gain use of some monster abilities
--job4a transform into some monsters

The "a" stands for advanced and would be an advanced form of the job. This way each Class could evolve into X amount of Jobs that you could unlock via quest lines. You'd also be able to unlock them all and advance them all but only be able to be one at any time. Maybe some of the names could be (advanced in parenthesis): Elementalist(Summoner), Evoker(Primalist), and idk what names could be used for beast master and morpher... I'm too tired to think much.

Maybe they could take Lancer as it is and flesh out some jobs for it that incorporates already like Dragoon and Dancer. Maybe to get Dragoon you'd have to have the pet class leveled some and the Lancer class leveled some (to say 30 like in xi (not too hard to get but still takes a bit)) though to be true to the series DRG was also able to use rapiers like a fencer. Conjurer could unlock white mage (to be advanced into seer) and black mage (to be advanced into black wizard and maybe further into sage with THM leveled high enough) while a mix of THM and MRD could produce dark knight and GLD and THM could produce red mage... idk haha

I'm tired (4:25am) and these aren't fully fleshed out ideas but I wanted to get them out and apologize if I don't make much sense. I'll come back rested and maybe edit it if it needs it or reply in a more coherent post.

tl;dr - combine DoM/DoW into disciple of combat. less class combinations (or save for advanced versions of jobs), more jobs unlocked by one class. still keep some "light" combo's for the obvious DRK/RDM/ETC. Advancements to some or all jobs.