I'll admit that's a very interesting concept you've presented there.

Minor correction, your Necromancer wouldn't be available to Tauren, given the fact they can't be mages at the moment. Similar qualms with racial restrictions of hunters, shaman and priest.

That's not a complaint, mind you, the examples you provided actually work nicely in including some of the obvious candidate races while eliminating other more less convenient ones.

Tauren don't really fit the bill for necromancers, but they make plenty of sense as gladiators, for example.