Let's face it. Even if you're an ever-other-generation camera buyer and minimize your lens purchases to, say, one a year, at anything above the entry level full frame camera level we're talking about probably well over a thousand dollars a year in gear purchases. Live at the high end of the model spectrum? Make that well over two thousand dollars annually. (According to surveys of site visitors, those of you reading this average far higher ;~)
Here's the thing I noticed in the DSLR era: at some point the majority of enthusiasts gave up on upgrading. In the Nikon world I follow closely, that didn't happen with the D70, but it started happening with a D90, and certainly happened somewhere in the D7xxx offerings if you were a mid-level user. It also didn't happen with a D1/D2 or D100/D200, but started happening with the D3/D300/D700 and subsequent models. It took a couple of pretty dramatic new offerings (D500 and D850) to nudge some back into active buying again. But note how many of those folk are still using those six and seven year-old cameras.
When I ask these "dropouts" why they are shutting off their credit cards, the usual answer I get back is some form of "what I have is good enough." They folk stopped caring about small refinements in image quality, new features, and even better performance (focus, frame rate). They simply didn't feel they needed more. To put it in the headline's terms: they stopped caring about new gear.
It's clear to me that the same thing will happen, only faster, with mirrorless cameras. The primary buying habit will go from upgrading bodies to adding lenses and then to not buying anything new.
The underlying question that doesn't get asked is this: does dropping out of the buying cycles also portend doing less photography?
Anecdotally, I'd say yes. Once the rush-to-upgrade craziness wears off, so does the need to prove you had to upgrade. You're not rushing out the door with the new gear to see what it does and show that off to everyone else who's noticed your buying habits (e.g. spouse ;~). The camera and lenses begin to only come out on special occasions (family events and vacations, mainly). This is what I refer to as "closet cameras," as they spend most of their time in your closet waiting for their next big opportunity to prove that smartphones are all you really need ;~).
I wrote about this many years ago in the film to DSLR transition: the camera makers need something that breaks through a large user problem in order to restart the buying cycles again. Originally, that problem was exposure and "fixed" with an automated exposure system. Then it was autofocus. Next, it was the review-what-you-just-took nature of a DSLR. Most recently it's been the see-what-you're-going-to-get nature of mirrorless.
I've argued for fifteen years now that the huge user problem that isn't being solved is get-the-image-where-I-want-it: the very thing that smartphones are really good at. It used to be that we either displayed images as printed (e.g. 4x6" one-hour prints) or in slide shows. Today, images are extremely ephemeral and live brief lives on the Internet. Preferably, immediately after taking them. And instead of keeping small photos in your wallet to show friends when you see them, you just pull out your smartphone and flick.
The camera makers have given lip service to this change in image viewing habits since I started my crusade for communicating cameras. SnapBridge has some origins in a talk I gave in Tokyo, for instance. If you've ever tried to use the features that the camera makers provide in their companion apps, however, you'll find that they stink.
They stink because they're seen by management as a "free feature" and thus the camera companies don't really invest any true, on-going R&D money in creating, perfecting, and maintaining them. Moreover, except for Sony, the camera makers are afraid that doing anything that makes a smartphone part of the photography equation is just admitting that the "camera" isn't the center of the universe. Tokyo still thinks the earth is flat and the stars, sun, and moon rotate around them. (How is that logically possible? If the earth is flat, how do things rotate around it?)
This all matters to those of us still trying to practice and engage in photography, either as high enthusiasts or professionals. We demand new gear, even if it only solves small problems for us, or provides us only a minor incremental boost in quality. But if the majority of the buying public ends up checking out after they've "got enough" of what they think they need, the camera market starts shrinking. We came dangerously close to a market size that would cause us to lose significant players with the COVID pandemic. Companies such as Nikon are no longer talking about growing their Imaging business, but rather milking it for as long as they can (excuse me, "sustainability strategy" in Nikon-speak).
The solution is simple: for-profit smartphone apps that actually work in tight conjunction with the camera. I personally don't care if the phone has to be cabled (USB-C has made it to the iPhone, hurrah!) or wireless. Just make the camera/phone connection really work correctly. I could wireframe the design of said app in a week. But I don't have time to code it, let alone test it against every camera that's made (even if by one maker, e.g. Nikon). It's not a rocket science project. It's a grind-it-out project, which means it takes programmer time and effort. And that takes money, thus it has to be a for-profit app, not an intern project that was done minimally.
So here's the question: would you start caring again if that app existed?