The thing about this new spec is that it's compatible with the GDPR in a way that could make adopting this a legal requirement, given enough lobbying effort. It'd be a long battle, but I could foresee a future where regulators require adtech to implement this spec to obtain consent.

That won't stop them from additionally using cookie banners, out of spite. But I suspect many websites that currently have cookie banners only have them because they believe it to be necessary, and it's hard to push back on it. If such a spec came to be recognized as a way to obtain consent by regulation, it'd make it easy to point its way, and at least end the madness of cookie banners on websites that don't need it.