I think the future will be a web browser running inside a VM and then the final DOM including all referenced resources go through a filter before being rendered. That way, it's impossible for the website to detect if you display the ads or if you just just load all necessary resources for rendering but mask them out.
The future will be “AI PCs” with a powerful on-device chip that can filter out on-screen ads, but enabled only by subscription.
Hmmm, that'd be an interesting startup idea!
How do ad blockers work exactly?
They're entirely manual. A whole bunch of volunteers write filter rules to block known ads. There's a big github where people can post issues about ads they've found, and volunteers will write filter rules to block them.