Apologies that I never added any comments of my own last night -- just put in the link and hit "post reply"! It was getting late.....
Many of us, especially those of "a certain age," were lucky enough to experience what I now think of as "the golden age of DSLR photography." That is, we bought the early Nikon Coolpixes, Sony Mavicas, Canon whatever and other first digital cameras, and then moved into the first digital SLRs. In my case, my first digital camera was indeed the first Coolpix, the 900, and I loved that little thing and moved on through a series of Coolpixes over the next several years. At some point realized that I was pretty much using the digital camera exclusively while my Nikon SLR (The N-90s) and its lenses sat in the armoire unused.....
One day I went to the local camera shop and bought my first digital SLR, the Nikon D70. It was like coming home again to the features I'd missed by not using my SLR. I loved that camera and sure enough, when Nikon brought out the D200, I bought one, and eventually the D3......and added to my lens collection over the years, too.
The mention of reduced incentive to upgrade makes sense to me; at some point for me there weren't enough incentives to upgrade any more, the initial excitement was gone and it almost seemed as though newer camera bodies were ho-hum, more of the same with maybe an additional bell or whistle added so I didn't upgrade. One day a few years ago a photographer friend, another Nikon shooter, came over for some reason and he brought along the new Sony NEX-7 that he'd just gotten. That was my introduction to the world of mirrorless cameras, which immediately intrigued me. I bought my own NEX-7 the following week.
As with Nikon, I have been watching various new Sony camera bodies coming-and-going and again have not upgraded -- yet. Analysis paralysis set in -- do I buy a new Nikon DSLR or do I buy a new Sony mirrorless? Just about the time I'd decide to do something, darned if something else wouldn't come along to make me think, "maybe I'll hold off a little, see what happens...." Nikon did that with their mirrorless Z series and Sony has done it with their additions to their line of full-frame mirrorless Alpha 7 series. I waited to see how Nikon's new Z cameras and new native lenses fared in the hands of actual users. Ditto with Sony's A7III and A7R III. Now both systems have released new camera bodies again -- gee, it seems as though I've been dawdling around an awfully long time!
As Molly mentions, in the beginning there was a lot of commentary about focusing issues with the Z series. There were also some complaints about only one memory card slot. Actually, if I recall correctly, though, the FTZ adapter was included free with the purchase of each of the two models at the time of initial release. Now, yes, I think for the most part it is still included in some kits. That FTZ adapter was a very important "hook" to get people who had many F-mount lenses to at least try one of the new Z cameras since they could also use their own older lenses on them as well. But, yes, there are still people (yours truly included) who hesitate at the idea of having to use an adapter and who prefer to go with native lenses. In my case Nikon has not released a native macro lens yet and so far there isn't mention of one on the roadmap, or at least there wasn't when I last looked.
The economy may have something to do with poor camera and lens sales in general, as there are many people in the US and also in other countries who are struggling financially for various reasons and so really cannot afford to purchase a new camera body or lens(es) and they hang on to what they have already. My hunch is that many who are still actively shooting on a regular basis (hobbyists, enthusiastic amateurs, etc., in addition to of course professionals who make a living with photography) are those who have the money and the time. Some who were already retired at the time DSLRs really became popular are now getting to a point where age is catching up with them and they perhaps physically can no longer handle their beloved DSLRs and heavy lenses and have either shifted to something smaller and lighter-weight or have given up shooting altogether.
It seems pretty clear that smartphones definitely have had an impact on the photo industry. Years ago I was always the one who had a camera at parties and gatherings. When I got my first iPhone, people laughed and snickered at the whole idea of it and assured me that Blackberry still ruled. A few years later I went to a party and sat there smiling in bemused fascination as everyone was running around pulling out their iPhones or other smartphones and snapping away with selfies and pictures of each other, the food, etc. Even I had left my "real" camera at home.
Smartphones have pretty much decimated the P&S segment of the photographic industry. Certainly I have found myself using my iPhone a lot more in the last couple of years than I ever did before. Sure, I can't step out on my deck and fire off shots at the distant ducks or geese and expect closeups, but when I'm at the store or out somewhere and see something interesting, the iPhone is at hand, ready to take that interesting shot..... So, it's easy to see how someone would think, "I don't need a big fancy camera, my iPhone will do just fine!" and if they ever had a P&S at all, which many younger people probably do not, it would be lying in a drawer somewhere.
Today consumers are faced with a lot more options than we had back in the days when it was just a P&S or an SLR or a digital P&S or a DSLR; now we've got m4/3, we've got DSLRs, we've got mirrorless APS-C and Full-Frame cameras, we've got Bridge cameras, even digital Medium Format cameras.... and technology keeps moving us forward into other new dimensions. Mirrorless and m4/3 both offer smaller sizes and weights which may make all the difference for some consumers. Others still need DSLRs for specific types of shooting (wildlife, birds-in-flight, sports), although I think Sony's new A9 II is trying to edge closer and closer to becoming the system of choice even as they are also adding longer-length new lenses as well. Each type of system has its own advantages and disadvantages, and it is up to the consumer to decide what will best fit his or her own photographic desires and needs as well as budget.
It is pretty apparent that Nikon and Canon both made a mistake in entering the mirrorless field so late in the game, having allowed Sony and others to get a real foothold in that particular realm and now they're trying to play catch-up and it might be too late. Over the years several members of NikonCafe have made the jump to mirrorless -- some to Sony's NEX series or Alpha series, while others finally made the jump once Nikon announced their Z series. I've been following comments on there and viewing their images. There have been a few grumbles about the FTZ but not as many as I would have expected. Molly has a point that it probably is just not a big deal.
Another local photographer friend who has been a long-time Canon shooter recently bought one in the new Canon mirrorless R series and he really likes it. I don't think an adapter was required for him to use his older lenses from his earlier Canons but I'm not sure, as the day we went out shooting together he was using new native lenses on his "R" camera. He commented particularly on the smaller body and lighter weight of the new setup, which was important to him and a big factor in his purchase decision over a Canon DSLR.
A friend in another state is considering buying herself a camera, and I have suggested that she look at all the options, do a lot of reading and viewing of images, also think a lot about what she plans to shoot and wants to shoot. The most important thing, though, of course, is that she needs to go to a camera shop and actually handle the cameras, see how each camera body feels in her hands. I've also reminded her that in buying an interchangeable lens camera she's not just buying a camera body, she's buying into an entire system....
None of us has a crystal ball here, but certainly things don't sound good for the photography industry as a whole and for Nikon, Canon and Olympus in particular. That is really sad.
As someone who has been using Nikon cameras and lenses since the early 1990s, I hope that Nikon can turn its bleak financial picture around and that by doing some restructuring and perhaps changing their marketing strategy that they and their cameras will indeed be around for years and years to come......