As to this child.. he will ALWAYS live with addiction. His Father is an addict, whether he is physically present or not.
If you love this child and would like to raise him as one of your own, knowing full well his Father could sober up someday and take him, do so. I would live in today and love this child and not stress over the what-if's of his extended family or his addicted Father.
What will happen will happen. Today is all you have.