It's not an argument, it's just a thing that happens whether you like it or not.
Can
you accept that the world is changing (as is usual) and the EU is on the way out, together with the world order that enabled it?
I don't pretend to know what comes next, but we can already see that it'll be "multi-polar world" with several "great powers" (no longer a single one plus its allies), and draw some possibilities from that. The EEC and later the EU was an american project for Europe, which rested on two premises that all participants could agree on: blocking the soviets/russians from dominating Europe, and keeping the germans from renewed regional hegemonic aspirations. But in the meanwhile the wold changed, the the russian threat collapsed and germany is again playing games. The EU's original goals were voided. And the third premise that made the US support the EU, that the EU would be the US' docile ally following its lead, is fraying even now as preferential trade treaties collapse and diplomatic differences abound.
This new "multi-polar world" is already one of continued crisis in the poorer zones, which are to be "policed" through interventions from the regional powers. And (unnecessary to say) kept from organizing to the point of challenging the regional powers trying to play hegemon in each region. These wars and refugee crisis are not going to decrease, quite the opposite. And the time will come when public discourse about drowned refugees in the Mediterranean will be only indifference or even "good riddance" stated openly (no longer muttered silently, as many do already).
Basically a return to the 19th century model of international relations. There is no place for a dysfunctional EU there, any more than there was a place for a HRE in the 19th century. It cannot unite because there are (at least) two major, conflicting political projects inside it.
The french destroyed Libya because it was threatening to weaken their influence in Africa, and are bent on using european resources (a "deeper union" with a "common military", just wait and see) to practice outright neo-colonialism ion that sad continent. It's going to fail because it'll clash with the other great powers: China, India, the EU, even Russia will intervene there also, and bleed the french and its allies until any european alliance they build collapses. Nothing new, colonial wars mark II...
The germans don't want to be pulled into that project, instead with to establish their own economic hegemony throughout Europe, or at least central Europe. But this will only increase nationalism in the affected countries. It's the same old failed german strategy... And when it fails (read: when german business is expropriated and expelled from those countries by nationalist governments) german militarism and revanchism over "historical claims" about "lost territories" will return. It was not so long ago that Kohl threatened to retake those territories by force if necessary...
These two (Germany and France) are the only states with a "transformative" agenda in the EU. All others are members only out of a mix of bribes (subsidies) and fear (of exclusion and being penalized). But even if they banded together they wouldn't be able to block these two inside the EU's institutions. And the third "great power" that did had an agenda (the UK, keep the status quo in Europe) has called quits. Which was a good call because it is impossible to keep the status quo: it's either the german of the french agenda. Either will end in disaster.
In this world where the military and economic power for interventions becomes crucial, there will be no room for "free trade", "international (financial) markets", or "free flow of people". There will be a "nationalist" crackdown on all these, borne out of the renewed competition between the great powers. The issue on the table is how the EU will break apart, not if.
Will these be just a thing that will happen whether we like it or not? I don't believe in political inevitabilities. But I fear that burying heads in the sand and pretending that the EU doesn't have these problems will guarantee that they'll happen, and it'll end in a very bad way. Denouncing the problems and dissolving the EU now, back towards a free association of countries that participate only in limited, unanimously supported projects, and exercise full sovereignty, is the best way to prevent both those destructive agendas from lead Europe to war.