It's likely the case that, given current trends, that nations like Poland and the Czech republic will be as or more prosperous than the UK currently is and that they will be magnates for young Britons seeking better economic opportunities outside of their stagnating nation.
Also when these same Britons travel to Ireland(!), France and Germany they will also notice that these are nations which are more visibly prosperous than they are on numerous levels. That's quite the change of fortunes from the 1990s and early 2000s when Britons were whining about Polish plumbers and it demonstrates just how much the UK political class has screwed things up since the late 2000s. It's more than Brexit in other words.
Addendum: this is obviously going to give a lot of momentum to those movements which want to cleave off Northern Ireland and Scotland from the UK as well. Own goal doesn't begin to describe what has happened there.