I think the reduction in alcohol consumption may be an enduring long term phenomenon.

Enduring could mean a few things. I think that in the grand sweep of history, it's more likely to be cyclical.

Ignoring the stretch around and just after prohibition up to the war, the low stretch in pure ethanol consumption in the US for the last century or two was 1947-1961 at around 7.6 litres/year. It rose sharply for a while and was over 10 litres/year around 1973-1983. The most recent figures seem to be around 9.5 litres. A lot of the changes can be explained by changes in the shape of the population pyramid, less by changes in human nature.

So, offhand, I would consider the scale of a major lasting generational drop in consumption levels, if we see it as you suggest, to be equivalent to a fall of maybe ~20% back to the figures seen in the prior postwar low stretch. Real dollar value of consumption might fall less, as people are on average richer than they were before. My investment thesis is that the better companies might have a slowdown or one time shrinkage, but will still be formidable businesses with extremely resilient and long-lasting income streams. That requires a discerning eye on what the new volume levels might be, but those "remnants" may well deserve a strong premium in valuation.

In some other markets like France, the fall may be more major and lasting, simply because there were extremely high levels a while back. Nobody here wants to consume the oceans of mediocre wine that used to be guzzled day and night, when consumption per capita was over 25 litres/year in the 1960s. (it's now under 12, but interestingly the whole of the fall has been in wine...spirits and beer consumption are flat in the last 60-70 years)

Jim