I think, as with everything else, it's all in how you write it. Compelling, sympathetic characters in a well-told tale will win readers every time.
The only caveat I'd add is there are always going to be some folks who are simply incapable of being sympathetic to an addict, no matter how well-written. They have their own reasons.
At the risk of taking this thread in a more personal direction, I'll offer that my father was an alcoholic of the abusive sort throughout my childhood. While I was away at college, he sobered up. It took me years to forgive -- and I'll never forget -- the violence and instability of my childhood, but he taught me that addicts CAN change. He did it with the help of a loving wife, and credits her with saving his life and, frankly, his soul.
So I would read your book, Fallon. Addiction may not be romantic, but a realistic romance can be built around the conflict of addiction.
Will Harlequin buy it? Probably not. But they aren't the only game in town.