Being able to do content recommendation for fresh visitors without any tracking effort of your own would be pretty cool. It will probably come with a dialog, so users will likely opt out often for ads or on page load, but not if they just clicked "show me movie recommendations" in your app.
The proposed designs never expose segments (err, cohorts, whatever) to the page. This machine works for managing targeted advertising in Chrome, and... that's it.
> cohort = await document.interestCohort()
I mean it‘s a proposal. I‘ll believe it when I can use it, but maybe actually look at the proposal.