The AMA classifies addiction (which includes alcoholism & codependency) as a mental illness. Better compared to Bipolar or Borderline Personality Disorder. Nobody in the world can predict whether an alcoholic will stop drinking and if so, for how long. I do know that the % is very low.
What's the point of trying to figure out someone? We can never understand what's really in someone elses head. Some alcoholics may feel guilt, many don't. In the end it's how we (the codependent) responds and what we do about our own issues.