I expect that tracking will just move to being proxied server side. It will be more annoying for the people setting it up but services will spring up to help. Little will change in the advertising and tracking space.
It just seems somewhat wrong that a browser with a huge market share doesn’t use any standards / rfc process and invents new ways of blocking tracking / breaking agreed upon specifications from release to release in isolation.
We'll be doing more stuff in standards first / in parallel now that more browsers are actively engaged in reducing tracking.
A lot of the more extreme thing we'll only do for sites that we've classified as a tracker. Other browsers put identified trackers in all kinds of penalty boxes that aren't fully defined by standards yet. (We happen to do the identification using machine learning instead of a curated block list.)
If social.example links to blog.example, limit cookie storage to 24 hours, no matter what is in the link.
At the very minimum it aligns incentives better for developers to think about these things.
And with IPv6 privacy extensions IP addresses will also be less useful for server-side tracking.
But most will be OK with their servers running Google, Amazon, Oracle BlueKai and Facebook code, the scariest ones by amount of data.
I recall these extensions are just optional. How many implementations actually implement these extensions? I recall Windows 10 had this broken for a year and almost nobody noticed...