20-Year Prospect
People love to drink. And in case you think that's a recent phenomenon, just remember something: Some very smart people believe that beer invented civilization (source). Even our closest animal relatives seem to enjoy the stuff (source). So if there's one thing you can depend on, it's that people will want to drink.
The question is whether or not the current "three tier" (as in manufacturer, distributor, vendor) model is going to continue. The fact is, distributors are literal middle men (and women), standing between where the booze is made and where it's sold. If you look objectively, there's no value added in that middle set. It just jacks up prices.
So why is it there at all? The short version is that it's the law (source). Any kind of change is going to have to result in a change to the law. Since these are state and not federal ordinances, that's a whole lot of change that'd have to happen. So it's probably not going to happen.
Additionally, since this job is mandated by law, automation (the giant bogeyman of all other careers) isn't a problem for you. Nope, the law says "person" and not "android," so you're safe. Technology will likely make it easier to tote around your samples and place orders, but that's about it.