One of the better signs is that they start trying to reconnect with people they have alientated. Usually with their children first.
They also seem to have to hit rock bottom first, and that varies for everyone as to what rock bottom is. But I'll tell you it most likely won't be anything you think 'rock bottom' should be for them.
As long as you realize that you're putting the cart in front of the horse by asking this question, then you'll be fine. If however you use this information to shoehorn his actions to fit your hopes and wants...then...smack your hand. : )
Experience is a brutal teacher, but you learn. My God, do you learn. - C.S. Lewis
Life is usually all about how you handle Plan B. - Jack3Beans
Listen without defending; Speak without offending - FaithinAK