If you look at the history of anonymity networks, you'll notice that tor totally replaced mixing networks. Considering the fact that mixing nets are more secure against government, with regards to email, it is interesting that the u.s only invests in and promotes tor.

But in a world where individuals have access to extremely powerfull tech, something has to be done.

I think the solution for privacy might look like something different. Maybe the government could read everything, but there would be some good transparency tools, ensuring proper usage.