A brexit could start chaos in the currency markets and make Bitcoin a safer option.
I just heard Amanpour interview someone warning against a meltdown of the financial markets. "The Pound might even go 20% down!", he said. So yeah, bitcoin, that may go down 25% overnight without any reason whatsoever, is a safer option.

Yes but your Bitcoin bank can't go bankrupt like your fiat bank. People won't like having their money in the bank taken to bail it out if it goes bankrupt because of chaos in the currency markets.