The biggest thing about this update is the adventure update, so the fact that there aren't NPCs yet in the NPC villages doesn't bother me too much. I think there will be too much to do to notice.
But the interesting thing is, if you watch the behind the scenes video, they say that one of the villages will happen near the spawn point. Seeing as we have already lots built near our spawn point, I wonder how that would work.
In keeping with Minecraft tradition, I suspect new features are only generated in new chunks, so there would be no NPC village magically cropping up near our spawn point. I am still considering pruning explored but undeveloped chunks once we go to 1.8 or 1.9, though. I doubt any of us just wants to wipe the slate clean.
An alternative would be to generate a brand-new world, then copy and paste the structures we built in our "old" world into a designated area. I could tweak the landscape enough so it's not too discontinuous, but even that whole process might be too radical for us. I am open to suggestions.