I want to start by saying that I'm against these measures but while all that is true, it only gets that bad if you try to enforce 100% compliance. Simply making cryptographic systems without backdoors illegal would have a large deterrent effect. It'd be the equivalent of the fact that locks on your doors don't provide 100% security because windows are so easily broken, but we still lock our doors.
First off making non-breakable crypto illegal would prevent such crypto from being used in traditional commercial products. Second, the government wouldn't have to attack the problem from the front like the article suggested. They could use their NSA spying capability (once gain no a big fan) to look for unauthorized encrypted communications. They already take special note of encrypted data use, and with it being made illegal they could directly legally target the users of such tech. The chilling effect of such a large scale NSA backed takedown would be huge.