I suppose, but I view this whole thing just like the migration from SD to HD, then HD to 4K. Or more on point, film to digital.
For numerous reasons, folks can't just simply move to new tech sometimes all at once. There has to be a transition period.
Now, then, such a transition period will not last forever. So yes, inevitably, those continuing with photography will eventually be on mirrorless.
Of course as long as DSLRs function and used markets exist, they will still live on. Just like film cameras.
Personally, I'm at a crossroads. I have the 5D IV and two lenses: 50mm f/1.2 and the 135mm f/2. Before I move to RF, I want Canon to offer the RF version of a 135 focal length. If that doesn't happen for a long time though, I plan to keep my 5D IV (even getting a backup one perhaps).
Moving to mirrorless for me is a bit of a domino effect. Yes, one can get adapters for lenses, but if I'm on the RF system, I'd want RF glass. Then there's the media. Oops, cannot use my Compact Flash cards. And I wouldn't want to use my UHS-I based SD cards either. Yes the LP-E6 batteries would work, but I'd want at least LP-E6N and actually the LP-E6NH ones.
Thankfully I have more than enough HD space so a move to roughy 50% more data (45 MP vs 30MP) wouldn't affect me at all. But for others, it may. Same goes for processing power; I have more than enough, but others may need to purchase new computers.
I will take a look at what the R1 can do when Canon releases it but right now Canon mirrorless offerings aren't well suited for fast action.
At this point, if I were going mirrorless and changing to a different lens system I would likely make the jump to Sony. Canon is going to have to sprint to keep up with Sony sensor technology.
And Sony is looking very good for dynamic range which makes so much difference in a lot of real world situations. Having Nikon as a captive customer for their sensor technology is also quite useful for Sony's development budget.
It will be interesting to see if Sony releases a relative of the Alpha 1 with a lower density (20-25 mp) sensor aimed at the upper end of the sports shooting market. Combining that sensor with the other Alpha 1 technology could provide a very responsive camera with even better higher ISO performance.
Interesting times ahead in the imaging market although the elephant in the room is the continually decreasing number of people who are willing to trade off stand alone camera performance and versatility for the convenience of ever advancing phone camera performance. I suspect the overwhelming majority of people born in the last two decades will never own a stand alone camera just like most are fully satisfied listening to a highly compressed digital audio stream reproduced by laughably bad audio transducers.
"Canon is going to have to sprint to keep up with Sony sensor technology."
You can say whatever you want about sensor vs sensor but the bottom line is Sony does not make a full on pro camera or lenses. The sensor is just one component albeit an important one but still only one aspect of a pro level camera. There is no Sony I would trade any of my 1 series cameras for. Especially back when I was working full time. Not one! Again my 2 cents and worth every penny.
I have been telling everybody the writing is on the wall about the end of the DSLR for over a year now. I went through this once already. Its not fun and not cheap but things change.
...Sony does not make a full on pro camera or lenses.
Ernie, we have been down this road before, yet you remain seriously out of touch with the fact that pros all over the world (but maybe not in Kansas) are shooting with Sony cameras and lenses and earning a living. My suggestion is that you read, study and learn. Because your view has no basis in reality.
The fact a professional photographer uses a certain camera does not make it a pro level camera. I know lots of working "pros", me too at one time, that use Rebels. Rebels were not and still are not pro level cameras.
To compare any Sony camera to a Canon 1 series is ridiculous.
We launched several RF Mount Adapters when we launched the EOS R line.
They're very popular, so they're difficult to keep in stock. Using the Canon branded mount adapters preserves ALL the functionality of your EF and EF-S lenses. That means they work exactly the way they were designed to. You don't lose auto-focus, f-stops, STM, anything. If you're using an EF-S lens on an EOS R camera, it acts like an EF-S lens - the camera goes into crop mode, so your images will be in 1.6x crop - just as you'd expect. It's really cool!
Here are all of the adapters: https://Canon.us/7t5sa