I'd be more interested to see what Switzerland, Norway, and the non-EU states of the Adriatic Charter do, given their proximity.  That's where we're likely to get a bit less notice, since anything decision they make is likely to be at least partially in response to how the EU states re-harmonize themselves.

But yes, if the UK does indeed leave the EU at any point before 2021, presumably they'd find themselves undertaking a similar decision.