I'm no expert, but... I can tell you that yeah, unchecked, alcoholism does progress. How? May depend on other things.
For example: One of my childhood friends is a construction worker. The first time he showed up at work and smelled like stale beer, he was fired. Went to AA, got sober, is sober to this day. He didn't have to take that proverbial elevator very far into alcoholism hell before he was smacked with a pretty damn severe consequence. And, for whatever reason, that was enough for him to hit rock bottom and get sober.
My ex, OTOH, worked in a job where two-three martini lunches and saying "hold my calls, Lucy" to your secretary so you could take a nap in the afternoon was par for the course. So he descended much farther into hell before he started seeing severe consequences. Which also meant his addiction was much deeper, he was much more enmeshed with the alcohol, and still to this day (despite not being able to be called "functioning" in any sense of the word) hasn't found motivation to sober up.
Someone pointed out to me that "functioning alcoholics" keep it together for longer (like my ex did) -- but once things start unravel, they unravel at warp speed.
I don't know if any of that helps. It's mostly just stories. But as you know, nobody can tell an addict they're in danger and need to stop -- so I guess what I'm saying is... don't jeopardize your own recovery in a harebrained effort to stop your relatives from drinking. (I feel like I've earned the right to use the word "harebrained" for those efforts, because I myself spent 20 years putting all my energy into getting someone else to quit drinking...)