Just as an thought experiment: What would happen, if legislation would make it mandatory for cookie layers to accept the DNT header (Do Not Track) [1] as input and forbid to ask the user if such a header is present?

Like

DNT: 1 == no cookies, except technical required cookies, like sessions

DNT: 0 == accept all cookies

If you don't like repurposing the DNT header you could also imagine introducing a new header for this purpose.

What would happen?

[1] https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/DN...