I bought Canon's original D30 the minute it was available. Subsequently I have had the 10D, 5D, and 6D. So I have witnessed and participated in Canon's glacial development cycles and customer-antagonizing feature decisions first hand. I have stuck with Canon because I felt overall their end product was still the best available for my needs.
In fact, I never upgrade until I can identify a shortcoming of my current camera that is preventing me from advancing my technique. I have been at that point for a couple of years with my 6D. The 6D2 did not address the areas of improvement I needed. Neither does the 5DIV. The painful realization is, there is not one single Canon camera that does meet all my particular needs.
(Disclaimer: my needs are not yours, so please spare me argumentation on that point. I am happy for everyone completely satisfied with their Canon camera and I am not going to second-guess your needs or satisfaction. So don't second-guess mine!)
On the heels of my long-building disgruntlement with Canon, has arrived the extremely affordable Sony A7III which is very nearly the camera I would spec for myself. Coupled with the fact that Sony is actively fleshing out their lens line-up, that third-party lens support for Sony is coming on strong, and there are now two high-quality EF lens adapters available, all barriers for me switching to Sony are removed. All I have to do is pull the trigger and go.
From my perspective, Canon is fiddling around while Rome burns,. This delay, while very typical of Canon, ignores the fact that this time, things are different. There is very serious competition that is meeting Canon in all full-frame market segments, from entry level to high-res to sports. I suspect whatever mirrorless full frame cameras Canon announces will have been subjected to Canon's usual market-segmentation analysis and rife with "camera crippling" decisions. They are sticking with all their other scripts and I see no reason they won't stick to that script too!
Bottom line for me, it's just about time to cut opportunity costs associated with remaining a Canon customer, and decamp to Sony.