You probably wouldn't want to run this in real-time on every site as it'll significantly increase the load on your browser, but as long as it's possible to generate adblock filter rules, the fixes can scale to a pretty large audience.
Depends on your machine and on the LLM. Could be doable.
I was thinking running it in my home lab server as a proxy, but yeah, scaling it to the browser would require some pretty strong hardware. Still, maybe in a couple of years it could be mainstream.