Technology always evolves, even in the pre-computer age
I've heard from a number of people who have predicted (even four years ago) the increasing popularity of mirrorless vs. dSLR... I think both of them have validity and do different things well
The one thing I see with dSLR is that the price point is lower, good for people starting out... And I think mirrorless is a more challenging camera to work with compared to a dSLR
True, technology evolves but quality is another matter. Years ago in the 60s I could commit to certain brand names that didn't magically stop working. I still have a Canon AE-1 and A-1 that works as well as the day I bought them in the 80s. But my days of using film cameras are gone for good. Digital is so much better, especially if one can master Photoshop.
That said, my present Canon DSLR still works just fine. Though whether there's a magic date in which it no longer performs well or at all remains to be seen. Though I suspect in a few years I'll be dead and someone else like my cousin will go on using that same camera.
The one thing I continue to hear from retailers is how the cellphone industry will eventually overwhelm the camera industry altogether. If it happens, it will probably occur after I'm gone. Some years back I thought the notion was absurd. Not so much now. Heard from one too many people who take non-critical pictures and are thrilled with their cellphones. That's just not me. And probably not you either.