There are independence tensions within European countries (eg. Spain/Basque, UK/Scotland).
You have to be a blind idealist to think this would work. There are going to be a lot of crisis scenarios for EU in the next few decades, refugees being the looming one EU failed to reach a consensus on and botched previously (that helped radicalise parts of it like Hungary and further alienated UK). The pending post COVID inflation/economic shock could also storm the Euro zone, Greece is still devastated from the "bailouts" in the financial crisis.