This is a legal problem and not at all a technical one.
It can be achieved today with current tech under the right legal framework, and it will never be achieved regardless of what tech exists without that legal framework.
As the OP I think I agree with you - the privacy problem (and the surveillance opportunity) is a legal problem - the right framework we get enormous benefits, evenly distributed and minimised downsides. The wrong framework and the benefits are concentrated in the wealthiest and the rest of us get the predatory downsides.
