What is realistically going to happen ?

My in laws have been alcoholics for years. I mean years, probably 10 or more. They drink beer from morning until night. They stayed with us for the past 4 days and together they drank a 24 pack a day. And get this. They weren’t drunk at all. That’s how used to it they are. They also only ate one of those days, and the entire time they did not drink a single cup of water. I know because I do the dishes and they didn’t use any cups.

So I know this is obviously bad. They’re functional. They don’t appear drunk. They go to work every day. But they are obviously alcoholics. I have no experience with this. Someone tell me what is eventually realistically going to happen if this continues?