I've found that as long as I'm willing to do things for people that they are perfectly able to do for themselves, they will allow me to do them and they will feel no responsibility whatsoever. With all due respect, until your son decides to get help for his drinking problem, there will, in all likelihood, be no job and no desire to do even the basic things necessary for his own well-being. At 40 years old, he is well past the age where he should have learned long ago how to take care of himself. If he wants to live in an abandoned van in someone's back yard, then let him. He's an adult and if that's how he chooses to live, then it's his decision.
I know how hard it is to watch our children (even when they are far from being children) make bad choices, but, we cannot live their lives for them and we cannot control their decisions. We just drive ourselves crazy with worry and alienate other family members. Maybe it's time to let go and allow him to reach his own bottom.