Future of the European Union

[Furunculus]

I'm still not sure why the clear alternative to "common governance" isn't intensifying deterritorialization of governance.

It isn't a clear alternative to anything, as international treaty law with its spongy interpretability and poor understood mandate is an exceedingly poor way to govern social interaction.
Further, we all clearly submit to common governance (with the possible exception of somalia), but there is no moral reasoning that would necessitate a nation of people assenting to a governance by a different polity if that was not their express wish.

Or is it another layer of my misunderstanding of your position and is actually a dialectical argument that considers instigating a crisis in the system as part of the path to a resolution (like Slavoj Zizek on global capitalism and the Trump election)?

Closer, but dialectical in what sense? I tend to talk about it in fairly dry terms, but the subject discussed is politics and political identity, and ultimately that is a matter of personal sentiment and emotional attachment.
I do think the Zizek argument has some application here, as I believe the EU to be a dysfunctional form of government in being unable to usefully represent the desires of its various people[s] it has a tendency to stasis. Which makes it an inflexible construct that has low adaptability to accommodate shifting circumstances.

Social engineering is always a gamble.

Agreed. A charge I would lay at the feet of the pro-eu elites in two separate parts; 1. with the likes of new labour treating mass immigration as a tool for social transformation. 2. on the part of eu policy makers that seek to enhance and promote regional identity within the EU such that national identity loses tractability and visibility. Was the context in which you raised the point?