How about ICANN making a rule and providing an xxx domain and slowly forcing the pornographers to that extension.
Allow the internet to police itself. Sure the pornos will complain and cheat, but if ICANN takes away their dot com and resells it because they keep turning it into a porn portal, well tough.
Blocking an entire extension would be a piece a cake for parents, ISP’s and phone companies.
The reason this hasn’t happened is because big money is being spread so pornographers have access to kids.
Can you define “porn” in an unambiguous way, not requiring any judgment on the part of ICANN or a court, in, say, one hundred words or less?