I stated that the market is changing and it is. The OP implied that cameras and all manner of gear will face an "inevitable curtain" which is nonsense. The big companies aren't going away but smaller companies, particularly those that specialize in certain products are going to have a rough ride. As cameras become smaller, lighter, and more capable how many people are going to want or need sling straps or camera backpacks? Filters? What do you want to bet that eventually you will be able to do just about anything you want in camera?
DSLRs are going away. That's pretty much a given. There is a market shift going on and sales may be down but the camera industry is certainly not headed towards any kind of "inevitable curtain". If anything, we will have better, more capable cameras in the future. The millions upon millions of cell phone users include a large percentage of people who never would have bought any kind of camera if it wasn't included in their phone. Those sales drive technology that we will all benefit from. Cameras in the future may resemble cell phones more then DSLRs, but there will be no loss in the ability to take high quality photos. If anything, the opposite will be true. Computers went through a similar metamorphis. It wasn't that long ago that if you wanted high performance you had to have a desktop PC. Laptops, tablets, and even cellphones have changed all that and we have gained, not lost anything in the process.

I assume you meant more expensive, not more expansive, and that is hardly a given. I recently bought an EOS R with an RF 24-105 L lens and lens adapter for about what I paid for just a 5DIV body when I bought it in 2017. There is little that the 5DIV can do that the EOS R can't do as well or better. As much or more camera for less money. It's a good possibility that we will see more of that. My reference to computers was just to point out that technology evolves and not always in ways we think it will. I wasn't equating the overall importance of cameras to computers, even though a digital camera is a computer with an eyeball and a neck strap. A digital camera is a want, not a need? I am pretty sure that there are a whole lot of professional photographers who would argue that point with you.