Of course, maybe it won't happen that way. But pointing out that people have gone to war over this stuff throughout history is not really helping.
Depends. I much prefer personal autonomy over national sovereignty. While I understand that many people feel strong national identification, I lost this long time ago, maybe because I felt Czecho-Slovak but my country split, maybe because I see the pain of my grand-father due to his Palestinian origin.
Fortunately, currently for me the soverenity of states usually result mostly in bureocratic annoyances, such as when a colleague of mine couldn't join me on a face-to-face meeting, because he is from Ukraine and would first need to obtain visa for Ireland.
Maybe the right level of governance is the one people choose from themselves instead of the one into which they were born.
I may be being overly facile, but "I consent to the government that I choose" sounds almost exactly like "I do not consent to being governed" to me. (Perhaps you mean that one gets to make such a choice once, rather than at will and repeatedly; but then when should such a choice be made?)
The EU has its flaws too, of course. Because of its necessarily top-down nature, it tends towards grand aspirational things which it can't quite achieve very well because national governments retain too much power, so it interferes in things where national governments care a little less, not always wisely. It should have more regionalism and subsidiarity.
And then?