I've just got to throw my two coppers in on the matter of "Necromancer".
I think that Necromancer should be a specialty, since D&D has traditionally had both cleric and wizard necromancers. A well-conceived necromancer specialty, along with a few feats to help build up your undead army and so on, is better (IMHO) than making a necromancer wizard tradition.
I would agree with this, with one caveat... that they change the name of the school and the keyword of which the "necromancy" spells are all designated, to something else.
So long as all those spells which deal with life, death, healing, and infliction are called "necromancy" spells... then ipso facto the Wizard Tradition that specializes in them is called a Necromancer. Which has always caused a disconnect in the past, as healing spells for 2nd edition fell within the necromancy school, much to people's confusion.
Let's change the spell keyword from "necromancy" to "biotics", and thus the Tradition can now becomes a Bioticist. A Wizard who specializes in the spells of the life cycle. And thus the 'Necromancer' concept can go back to being open for any classes that deals specifically with the undead.