If he gets withdrawals, you can always drive him to the hospital or call 911.
As long as you keep buying him booze or giving him money, he ll keep drinking. He has no incentive to quit: he lives rent free with someone who buys him his poison and he does not have to work.
If nothing changes nothing changes.
If you decide that you don't want to keep living like that, then you will have to start taking action. Sometimes change can be very uncomfortable.
Ultimately, it's your decision.
Check out the friends and family forum. you ll get more feedback there.