I’d say that’s what the D6 and 1DX-MKIII are for both these brands. Let’s face it they both want new lens sales. Stopping DSLR does exactly that.Canon suffered from mount change years ago. Went from FT-b to EOS. Hurt a bit but in the end ..
Right now, unless either canon or nikon offer to retrofit the long glass, all dSLR glass will be out of date (soon or later). Speculation is not more dslrs. How knows, perhaps both Canon and Nikon have will one last hurray. The short flange distance, as I understand it, is a real plus for lens design so ???