1. create our own porn at home and (soon)
2. have home orgasmatrons.
Parents have complete control of the Chat/Porn server and since the orgasmatron necessarily has all your desires stored in its LLM (Large Lust Model) it trivially knows your age and will lock you out.
And internet porn can be banned regardless of age. (that's only half sarcastically said).
Demand for home Large Lust Models and orgasmatrons will soar. You heard it here first. Opportunity for entrepreneurs. And these home-based products are the only way to keep porn away from kids (if parents don't care now, they never will) and to maintain privacy on the internet.
Every place where I've worked in I.T., the rule was "No porn downloading at work. Porn belongs in the home." (especially in the days of slow home modems)
And to be really enforceable, all offshore sites would have to agree to the scheme, including certain Russian ones who are glad to pollute our children's and adults' minds with porn, propaganda and conspiracy theories.
Lastly: There always was and will be media. Micro-SD cards now? If not phones, thrift store picture frames and RPi's. "Porn finds a way."