You start with one false technological premise above, then proclaim that pools can create a better mix-net (and I know you don't realize that is the only possible solution to remain hidden) without even comprehending how a mix-net amongst a few pools would be trivially easy to unmask. For a mix-net to work, you need a lot of varied users of the internet involved, meaning you need to create the high-latency improved Tor I have called for. This is the Dunning-Kruger effect (sorry not wanting to ad hominen, but factually this is exactly Dunning-Kruger).
Again, we're engaging in hypotheticals. Bitcoin isn't the only protocol that wants a better privacy. All I'm saying is that TOR is pretty good and most of the sites that have been shut down were just sloppy. Where do you think the governments get their hackers? They get people with little motivation to assist them, usually through coercion. While I'm not making the Libertarian argument that govts screw up everything, I go back to my point that people tend to resist ridiculous laws.
I don't know enough tech to assess your "technologically plausible solution" but I will say that there are plenty of people, if not governments, that will be interested in such pursuits. I also agree with franky1 that individuals have the power to resist and demand due process in the light of day. Bullies should never be tolerated, especially in positions of authority.
Our weakness is our own myopia and hubris ("Bitcoin is better than sex") ignoring our weak points and just expecting "someone" will always provide a solution and not too late.
Worse myopia is franky1 not willing to admit Bitcoin's block chain can't be untraceable and unlinkable in the current version of the protocol.