If "generic" NPCs are implemented, chances are that most players will just overlook them. From what I understand, you want NPCs who have a chance to be good but you really have to work them up to be good. The two Icewind Dales had a system like that. You can create a new NPC from scratch whenever you want if you've got a free slot open but he'll be hard to level up and protect once you get far into the game. And you know, that worked perfectly fine for Icewind Dale. But in Fallout, with unique characters, you're option to make new NPCs from scratch will just be time consuming since a unique character will obviously be better.
Example:
Starting off, Cassidy has got 80 HP and he's a damn good shooter. And that's just his starting off point. When compared to, say, Tom the Town Crier whom you've recruited from off the corner of the street. Being a first level NPC, he's got maybe 30 HP and you can give him a gun if you want to be shot from the back.
Only use I can see of "generic" NPCs would be for cannon fodder. And I highly doubt the developers would waste time and resource to program in cannon fodder.
Besides, if Black Isle mirrors Troika Games (which it really should considering the success of Arcanum) there'll be enough NPCs to keep you sated. The Temple of Elemental Evil will have dozens of followers to recruit.