It's true, there is no way to know if/when the final push happens. People do decide to and actually get clean, but there's no way to measure sincerity, it just happens. I definitely think having your own program and coping skills is something you can control and could be quite valuable for you.
It is true that addicts have to make the changes on their own, but unless they are abusive or harmful, it's not an absolute, 100% thing. He has to fix his own problems, but if you drop in now and then for support it's not going to harm, so long as you both know it's essentially his problem.