we're slowly running out of catastrophes other than technical ones. it's becoming more legit by the day worldwide. china's dead and if it does come back it'll be a meek zombie.
i'd say right now poloniex failing and some type of disaster when attempting to scale, either no scaling or the process screwing up.
Users losing their trust in bitcoin as reliable and viable currency because of the unresolved backlog issue and the kindergarten shown by the operators (be it miners, core developers, who cares?).
This is by no means theoretical, it's happening right now. Very likely, it's irreversible as well.
if people are losing their trust then why are they paying so much in fees? i agree that it can't continue forever like this but it's a sign that usage isn't falling away.