Where you are in this relationship is not easy. Yes this talk/boundary setting could help him to seek recovery. Or it won't. So in the meantime, just figure out what you need and keep the focus on you. Do not try to manipulate threaten or suggest anything to the all knowing Gods (As) because they have it all figured out already. They will all come around in their own time or not. Some sooner than others. I did learn one thing when I set my boundary. He did seek recovery. He felt backed into a corner although I didn't back him up there. He did it to keep his daughter. I don't care what the reason was, a sober father has to be better than an active one. However, in the end, take the alcohol out of the *sshole and you have a sober *sshole. At least that was my experience.
I hope your meeting goes well. And what I mean by well is that you walk away feeling empowered and good about yourself. Whatever the outcome, it will be the right one. If it doesn't go well, meaning you go back to some of your old habits and patterns which are hard to break, it's okay too. This is a learning process, baby steps. Everything is a lesson and we will be presented with them over and over until we get it right. I am getting better with lots of practice.
Peace
Jen