I agree that supercookies and header enrichment should be prevented whenever and however possible (e.g. header enrichment will be solved by requiring encryption à la Let's Encrypt), but fingerprinting is a lost battle that we should all give up on.
We will never be able to solve fingerprinting without upheaving the entire web platform as we know it. So many web APIs are simply not possible without exposing some UA capability and configuration variance. For example, it is impossible to support WebGL without exposing additional UA variance for fingerprinting.
Computers will always have varying capabilities and configurations, and developers will always need to consider some of them. A world without fingerprinting is a world without the modern web.
It only takes ~30 bits of entropy to uniquely fingerprint all ~3 billion internet users. We already expose this much variance entropy, and it is only going to increase as the web gets new features.
I implore you all to simply give up on fighting fingerprinting. Try to stop worrying about it, as there's almost nothing we can do short of the nuclear option of removing every API that exposes UA variance (which will make the web less useful).
We have already lost, and every new feature makes the hole a little deeper. The hole is already too steep to escape, so accept that you will be tracked by colluding websites whenever you browse the web.
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The W3C page comes to roughly the same conclusion, but recommends a very drastic and dangerous solution: legislation. I fear that legislating this issue will legitimize only select pre-approved uses of UA variance entropy, and will hinder developer innovation in the long run. I'd rather be fingerprinted than be held back by legislation as to what browser data I'm allowed to read, and in what manner I can act on that data.
Please do not lobby for legislation in order to fix this problem. W3C's proposed solution will most likely only cause more harm than good. I would be deeply upset if "intent to fingerprint" became an actual crime.
One example of something useful that such legislation may make illegal is my navigator.hardwareConcurrency polyfill[1] that runs a timing attack on your CPU (not unlike "The Spy in the Sandbox" linked to in the W3C page) to figure out how many cores you have. This information is actually useful for optimizing heavy multi-threaded webapps, but it is also directly useful for fingerprinting. Future legislation could make it so that using my polyfill, even for benign purposes, counts as "intent to fingerprint".
People do not deserve jail time or fines based on if a tech illiterate jury judges you to harbor "intent to fingerprint". The future will be a very scary place for developers if you actually have to worry about this.
[1]: http://wg.oftn.org/projects/core-estimator/demo/