I and Tom Wark, at fermentationwineblog.com have had an ongoing debate over whether or not marijuana legalization is a threat to wine sales. For a long time, my belief was that marijuana legalization will not lead to a detectable drop in wine sales, (see here, here, here and here.)
Then, as I saw more and better quality evidence, I began to equivocate more, (see here and here.) Basically, I noted that the preponderance of evidence indicated that cannabis legalization likely would reduce alcohol consumption, but not necessarily wine consumption. But I was far from convinced of even that point.
Rabobank just put out some great analysis that I think has shifted me further toward seeing marijuana legalization as a threat to wine sales. At this point, I am pretty on board with Tom's conclusion. I think we need to see cannabis as a possible threat.
That being said, Rabobank's analysis is based on the assumption that increased cannabis use results in decreased wine consumption and that intentions expressed by consumers are strong predictors of future behavior. I am not certain of those two assumptions. I would also note that Rabobank's analysis seems to indicate that legalization will primarily hurt lower-end wine sales.
One belief of mine that hasn't changed: that only time will tell what effect legalizatoin has on wine sales.