That was some good thoughts. I have thought about the same things.
I think one important thing to understand, is that there always is the risk of a flash like this.
And the flash will always (i think) be down.
So i would pay much caution to going long on margintrading in currencies with a lot of traction and movement.
This also leaves the opportunity to put in long options, at places in the graph where the accumulative forces in the volatility would have started.
Stay safe! :D