This is already playing out with Safari’s Reader Mode. Sites adapt and update their content so that Reader Mode doesn’t work and ads do.

I don’t think the gov’t can make adblocking illegal, nor do I think they will even try, but yes websites will (and already are starting to) use anti-block measures. It’s not even hard technically, if ads are served as content from the visited site’s domain, rather than iframes from other domains.

Will companies give up on advertising? I predict: Never.