One tweak to the rules and all of a sudden not only do porn sites have to verify the age of their UK visitors but also anyone connecting from something other than a residential ISP.
The more troubling thing about these laws is enforcement. The threat of fines only works against websites that map to a business entity. For anything else there will surely see a ramp up in the size of The Great British Firewall Ruleset, edited by the courts, and distributed to the Big N (5?) ISPs.
What will become of the smaller ISPs that refuse to block illegal sites?
Which sounds like a silly question ("of course the marketing is BS") but why even bother marketing if the core value proposition of your billed-monthly service doesn't work? Seems like a waste of money since you'll at most get people for one month when they cancel after realizing they can't watch Canadian Netflix from Florida, or whatever.