I'd say that such kind of issues is going to be less and less important in the EU frame, in particular when UK will adopt Schengen treaty (free flow of people and no customs through internal borders) and EMU (common currency).
For instance, our German speakers who live in Alto Adige/South Tyrol are becoming less and less vocal in their quest to leave Italy and stay independent or re-join Italy, considering the large autonomy they enjoy plus the ability to cross the border and trade with zero hindrance.
However, a compromise such as that Cywr mentioned is highly probable, also because of EU good offices (there have to be zero disputes between EU members for everything to go smooth)