Considering these things can shape shift into whatever they want and hide in plain sight, I find it a little hard to believe that we killed them all.
For all we know there's one laying low in the Tower as a desk lamp or a pulse rifle or whatever, how would we know for sure?
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If I recall they are driven to interact with people and grant wishes. That’s why the one Saladin was trying to kill, instead of trying to avoid him or kill him, wanted to grant him a wish. They aren’t normal and think differently. They may pull one out of the woodwork for a seasonal story. It wouldn’t be lore breaking to say one survived.