>>77741958His power is literally to make people do what he says. He could just say 'Forget I was ever here', and he's done.
You could argue that since his power doesn't last forever that should leave a time limit on the memory, but how can you remember something that no longer exists?
Despite that however, if he destroys every trace of his existence - he's very eager to have tapes of him destroyed and has the only copy of his parents research - and someone DOES remember he exists...who's gonna believe them? You saw the interview scene. People made up crazy shit that wasn't Killgrave. A mind controlling man is just background noise unless you're actively looking for it.
That being said there are other metahumans. Bucky as Winter Soldier would count, since I doubt he's not been upgraded by HYDRA. Which is another example of a cape existing but not being in the public eye. He was a myth in the espionage field. Not a real threat, but a myth. It was the spy community version of the loch ness monster.
Nuke, if they're going to follow the comics, is something like the seventh or eighth attempt in Project Plus, which means there's various other experiments out there. Cage proves that in fact.
