It's an interesting question. And I'll comment that I definitely don't think IPAs are a fad.
Sticking specifically to the area of packaged alcoholic beverages though, are we REALLY seeing a move toward bitter? The IPA certainly seems to have a stronghold within the American craft beer industry, and although I'm seeing a little bit of a move toward more European styles, compared to 10-20 years ago, IPA still dominates this segment.
But craft beer isn't the fastest growing segment within this market. White Claw style seltzers and ciders plus other spirit-based "ready to drink" beverages, are currently the big movers and shakers. And although some of these have "lemon" or "lime" flavors, I don't consider any of them to be particularly "bitter." Not in the way that American IPAs are. Most of them range from neutral to very, very sweet.
And then of course the dominant packaged alcoholic beverages are still the macro-beers, none of which would be considered "bitter" for the purposes of this discussion, either.
So is "bitter" actually growing in this market? Or is it just a perception due to the ubiquitous nature of IPAs at the types of places you and I like to go drink?
And there's another possible take... Maybe the percentage of people who like bitter is unchanged, but that the market has changed to better cater to us?
I.e. let's say that 95% of the population are the "normies" who like sweet stuff. And that 5% are the defectives like me who prefer bitter.
Well, if you have a small regional brand, are you going to craft out a product line to cater to that 5%? Especially if you're trying to place it on supermarket shelves where they don't want to stock it for 5% of their customers, many of whom may not even know that the product exists? Especially in a pre-internet age when you don't even really realize that 5% market exists, maybe THEY don't realize they exist b/c nobody's ever catered to them as only 5%, and they don't even know how or where to seek your products out?
Fast forward to increasing conglomeration of brands. 5% of 340M people is a lot more than 5% of 20M. That 5% has now had enough products in front of them that are bitter that they know who they are, and they what they're looking for and how to find it. That 5% will complain to the supermarket if they can't find the product they want on the shelf--or more accurately will seek it out elsewhere and the supermarkets will recognize that they need to stock those products.
Maybe it's just that defectives like me are part of the "long tail" of the distribution. Markets 20, 30, 40 years ago weren't well set up to serve "long tail" customers, but that's changed. Not because there are more of us defectives, but because our preferences were simply underserved before, and now we're being adequately served...