Why? Why do you not want more classes? Does it harm anything to add more? I'm honestly asking.I understand you desire for an "arcane" version of a half-caster, a kin to Paladins (divine) and Rangers (primal), but the last thing I want to see (personally) is more classes in D&D.
It could work if they decided to nuke half the classes in D&D 6e, but I personally don't like that route.It actually got me thinking a bit about going the other route... Make a warrior/half-caster class, with subclasses of "Gish", Paladin, Ranger; where by choosing the subclass you are choosing whether your half-caster is all about arcane, divine, or primal.