Intriguing... I like door #2... with the side effect that it returns Szass Tam to true life... I think that would make him more dangerous in some ways, and make him more interesting as a villain. I'll have to track down these other speculations by you, Ayrik, and others.
Playing in the Realms since the Old Grey Box (1987)... and *still* having fun with material published before 2008, despite the NDA'd lore.
If it's comparable in power with non-magical abilities, it's not magic.
I like it, too. But I'm not seeing it happening in the near future. Thay's the only undead realm in Toril. Its relative uniqueness would undoubtedly make it stay that way for a while.
Oh, well, given the coming of the Eminence of Aurant, one may say Szass Tam might be eventually written out...