I suppose all alcoholics could have been characterized as "problem drinkers" at some point in their drinking history. Personally, I never went to the hospital, and never lost a job, but I am certain that I am an alcoholic. The fact that I haven't had a drink since Dec 2009 doesn't change that.
As to predicting a drinkers future consequences... that's a fools errand in my opinion. That sets the stage for "passively managing" an alcoholic's consequences... waiting in the wings to rescue the drinker when the inevitable occurs. I say inevitable because in my experience anybody who goes to the hospital 15 times from alcohol and continues to drink will either return to the hospital, quit drinking, or die. More to the point, if 15 trips to the ER isn't enough evidence for him, there's nothing you or anyone else can do or say to convince this man that he cannot drink normally.
One very hard lesson I have learned in recovery is that when I care more about someone else's sobriety than they do, I am of no use to them and I am choosing to make myself an emotional slave to their choices. In other words, it's a lose - lose proposition.