As an old fart, I am not much of a participant in crypto currency but I get your drift and anything that aids in taking back power from those who have exceeded their authority I'm all for.
I have been examining sovereignty for a few years now. Who/or what is sovereign as you suggest comes from a position of power. Sovereignty also has to do with contracts and jurisdiction. I've got a lot of concepts bubbling in my mind and a few of them involve the Holy Roman Church, The British Crown and the US Federal Government. Foremost is that the People of The united States of America defeated the Sovereign British Crown (the King ceded sovereignty) and were supposed to have seized sovereignty for themselves. To mucky the waters, the American People have largely given up their sovereignty to government through sloth and contract fraud. Going back much further, the Holy Roman Church declared itself trustees of the earth and everything on it to hold in trust for Jesus until his return and as Trustees they think they get to manage (or farm) everything. Much more on these concepts from me later on my blog but it is all in the mind.
Well it's a pretty simple definition: "exclusive omnipotence over an item". And that power could be challenged but it can't be taken away without it.
By default sovereignty is only achievable if proper defenses can be mounted to defend against thiefs. In a State, it's not the contract that secures the property, but the tanks and the nukes. Internally of course a State has internal laws to treat it's subjects, but this means that the subjects can't be sovereign, so an individual can't own property, since he would need an army to defend it.
However cryptographic property doesn't need an army to defend it. It's already secured by the laws of physics, the supreme law sort to speak. And that is by default more preferable than to have large masses of people being organized for your defense.
So I believe with privacy enhancing technology and cryptographic property, the individual can regain it's sovereignty.
You are on to something and I hope you are correct about cryptography being an aid. As an old timer I have a problem with electrons using 1s and 0s as islands of proof, storage and safety. Good luck to all of us. We're going to need it.
It's easier to hide electrons than bars of gold.