All being well, the countries of the UK will seperate out as independent members of the EU:  they were united originally by outside threat (which, so we must hope, has disappeared) and the internal threat of eternal English interference in everyone else's affairs, for which there is now no necessity.  There is no reason why this shouldn't be an entirely friendly process.  We still have much in common, but England is too populous for us to co-exist happily in one state.  There is no reason that the Six Counties should join Scotland or that Scotland should want to have them.  They are part of Ireland which is distinct from the rest:  in the Republic the Protestant population was reduced from 13% at Independence to 6% now, which does not fill the non-Roman-Catholic population with enthusiasm for total union, so the chances are that the North will have considerable autonomy for centuries yet.