That's why you have backups.

I agree that having full control over your identity has risks as well as benefits, though. I expect that we'll eventually see security providers arise that have user-friendly account recovery tools. Due to the plug-and-play architecture of blockchains, that sort of thing will work automatically without any need for organizations like Aragon to integrate with them.

Exactly.

So if Facebook ran on Aragon, and the shares got hijacked, tough shit? Zuckerberg can't prove himself? Some guy in Yekaterinburg is the new CEO?

If history is any indication, you collude with the miners and hard-fork.

They have incentive to do that, because their work becomes worthless if ETH were to lose value because that kind of theft would destroy user confidence in the cryptocurrency.

I think the rest of the world would call that state of affairs a 'bubble'.

Now what do you do once a court hands down a ruling requiring said shares be transferred to a given person?

Guess what, they're not going to accept "we can't" as a valid answer.