Probably not strict enough. ISPs are just going to shrinkwrap their contracts with an extra clause saying they're selling your data unless you write them a lett

Probably not strict enough. ISPs are just going to shrinkwrap their contracts with an extra clause saying they're selling your data unless you write them a letter to some address which they will check at a ridiculously low frequency or have to call through a call center and deal with every salesman and their brother and sister flabberghasted at such a request while passing it on to their "superior" for an hour at a time while you sit on hold waiting... and in the meantime will sell your data. The law really should have made it completely opt-in only (which nobody would reasonably do) or just bar it completely. They already know all the tricks to stop people getting out of their contracts, they're just going to start applying that to this kind of opt-out situation too.