Let's be realistic about this - he's going to die. He's going to die because he's got an untreatable addiction and because, more importantly, he doesn't want to get over it - because if he did, he would have by now. You can have all the help in the world but if, deep, deep down, you don't want to stop then you won't. Two words: George Best.
I've had family experience of both sides: a brother who did want to stop, and did... and someone else who said he wanted to stop but didn't despite all the help you could ask for. He's dead now.