I think that's not the question - the question is if they can escape being locked out of the EU by getting an EU passport.
Thanks t43562, that was indeed the question.
Interesting reference to being locked out of the EU; I must have missed the declaration that post-Brexit we British will be barred from travelling to EU member states. More Project Fear?
Perhaps not so much locked out as being not quite as welcome as before. After all, it's the Brexiters who are all about ending the free travel across the continent, and common sense tells me that it might work both ways should we vote to leave. Not so much 'fear' as making contingency plans. Er, my friend that is....