Following through on the OP, we are approaching 100 days in the Trump presidency. I am not sure what tomorrow is going to bring. I certainly am not going to speculate what another 100 days is going to bring.
Same for cameras. I have a bunch of cameras in my drawers, and I am not sure which one I am going to use to tonight to photograph in a jazz club. Last week, it certainly wasn't going to be the Fuji GFX, but I may bring it tonight after last weekend's surprise.
We live with an industry that adheres to a Moore's law ethos. You are obviously having fun speculating, but you seem to be doing it along the pathway as we know it. But consider:
A. One of these days, Canon is going to have to make a serious run at the mirrorless.
B. PhaseOne, if it is smart, will address the GFX 50s and Hasselblad 1DX. I went for the expensive poor man's version of PhaseOne in the form of a Leaf 50 back. In two years it has suffered significant depreciation. With medium format now available at a third of the cost, I am very reluctant to repeat paying extreme premium prices. I don't need PhaseOne's seismograph, focus stacking, or warranty program. They've been at longer, but others will catch up in terms of getting the most out of a sensor. Assuming others share my perspective, PhaseOne is going to need to respond to this newer form of medium format.
C. I received a message from a friend last night out of the clear blue. We had messaged eight months ago about the X1D. As far as I know, he is not in that game. Yet, he was saying he would trade in two camera systems to purchase the Sony camera announced yesterday--20 frames per second, no blackout, silent shooting, 24mp-- if he were seriously shooting concerts. Based on his tone, I don't think he will do it tomorrow, but I think he is giving it serious thought longer term. Note: He is taking less pixels, but he is impressed with significant advances in other aspects of the technology.
D. You, like many others, seemed to be knocked out by the Otus lenses. Given the price of those lenses and the willingness of many to pay it, I have to believe there are other companies thinking about developing premium lenses.
For me, the only thing I can even begin to predict about the next five years is that I probably will not own a Canon camera and set of lenses unless Canon does something different. Time has answered the question. I now only use my Canon for Macro work. It used to go everywhere with me. Simple natural attrition.
In short, a five-year roadmap strikes me as pretty fanciful. Too much is happening. As I said, I don't know what equipment I am going to use tonight.