I think its wishful thinking that all they will require is a checkbox to verify age
I think the purpose of any new laws of this type will be to keep kids out of free porn sites, not slow them down a few seconds. The problem I see is that the lawmakers arent making the parents accountable for their own children. It should be half on our shoulders and half on the parents. We add some standardized code to our sites and then the parents install some software that blocks sites with that code. I dont think theres an adult webmaster around that wouldnt be happy as hell to keep kids out of their sites and the same goes for parents. But the lawmakers have their heads too far up their asses to make it happen.
If such a thing ever does happen it will be interresting to see what it does to traffic and sales.