After the ruling of USA v David Nosal in the Ninth Circuit Court, a news article "Federal court rules that sharing your Netflix password is a federal crime" indicates that this would give companies additional reason to say that password sharing, breaking ToS, is criminal. While it would be bad publicity for these big media companies (Netflix, HBO), how would a large internet company use the criminal ruling against customers (in the USA) violating the ToS? This is considering beyond specifically closing/canceling the account.
The leverage that a company would have is that if they know of such criminal activity, they can contact the competent federal authorities (or state authorities since there are state analogs of the law), seeking prosecution. That leverage could have deterrent power, if they post warning signs pointing out that computer fraud is a crime punishable by jail time and so on. There is the distinct possibility that such warnings would have the same effect as the FBI copyright warning that you see on movies, that is, people will see but not look. As for the "news article", then claim that the court rules that sharing your Netflix password is a federal crime, but they don't give any evidence of such a ruling. The dissent wanted this to be about password sharing, but a dissent is not what's called a "ruling".