I struggled with the necromancer for a long while when I had an idea for a campaign once that heavily involved necromancy. Mechanically and thematically. I was trying to decide between an arcane villain and a divine villain. The more I looked at it, the less an arcane necromancer made sense.
That said, I think I would prefer to see a divine-powered Necromancer class as opposed to an arcane-powered one. Not necessarily as a priest of the undead, just that the pure necromancer has a divine power source. Let him work like a "wizard" in some respects, with research and the flavor of his spells, perhaps... maybe seeking out the lore of unnameable, forgotten gods or cults instead of being a worshiper of a "current" god. Cthulhu-style "divine." Something "Other." Something that really brings on feelings of dread and creepiness.
In essence, fold the current arcane and the divine necromancers together under the divine power source. Not exactly a priest, not exactly a wizard, but somewhere in between. Make the base necromancer a ritualist and/or cultist of sorts, allowing for people to add more flavor one way or the other.
In D&D, there are gods across the 'alignment' spectrum with portfolios or domains. There are gods of life and there are gods of death, for instance. Most divine energy comes either in the form of "Positive Energy" which is the power of healing and creation, and "Negative Energy" which is the power of death, unlife, and 'oblivion'-style destruction or degeneration. By channeling positive energy, undead things can be turned, and by channeling negative energy, undead things can be commanded.
In short, life is "holy" and unlife is "unholy" but both are the province of divine Powers. But then, you've got arcane necromancers. Which suits some fiction, but really sticks out like a sore thumb in terms of both D&D game mechanics and the default cosmology.
I always saw wizards as people who wake up in the morning trying to decide how they were going to alter their little corner of reality, or which elemental forces to start tossing around.
The loss of necromancy for wizards doesn't really bother me. It was something that I never felt worked out very well.
Charming and mind-affecting, I can understand why they nixed that to try to beef up the psion's forte. And I can't say I won't be glad that the Charm Person at 1st level monkey wrench will be gone. But I'm more ambivalent about that than anything.
An Illusionist class sounds like fun. It's such a big thing that I'm glad it will be getting its own class. Being able to replicate anything, in terms of perception at least, really deserves more attention under a rules system than one small corner of an already powerful class.
So, I'm glad for the Illusionist, overjoyed at the necromancy thing (and praying they get it "right" when they do bring it in), and ambivalent about the beguiler.
Mechanically, many of these powers - necromancy, summoning, charming, and other stuff - just didn't get as much attention as it deserved to work properly in the grand scheme of things. I consider each getting its own class as a good thing in general.
I also think we need to see how the class training feats and the multiclassing rules will work before signaling the death of the "old school" D&D wizard. It might be possible to replicate a wizard generalist using them that incorporates all the "lost" arts.