Funny that this rumour isn't showing up on Canon rumours that I can see. With this C-19 economic fallout all bets might be off.
Even though the market space (and how !) and watered down technology from the 1DX III readily exists for a 7D III, you'd have to now wonder whether it will ever get off the ground ???
I also wonder the same about an R7 (though perhaps that has moved to better than even money ?) The R5 when it arrives, can be thought of as a ~17.5MP Mirrorless 7D anyway.
Prior to this C-19 disruption, CaNikon were firmly running a DSLR/ Mirrorless tandem development program. It seems that there are enough diehard OVF users to ensure some ongoing DSLR's, and that they possibly have the AF edge for now (at least for CaNikon). Now - who knows ? The Mirrorless products certainly have an underlying cost structure advantage.
Perhaps we will still see DSLR development though it doesn't look promising for anything unannounced, for the rest of this year at least .....
If an R7 does come along we can only hope that it will be at a fully professional level. I think it still means using adapted glass though as the 100-500 f4.5-7.1 rumored seems more consumer orientated - if a handy lighter weight rig.
I also disagree with the rumour linked regarding the EOS-M. It seems quite a popular format in parts of Asia at least, and Canon are continuing release of lenses /models. With it's smaller form factor, I can't see it being replaced by any APS-C R range. Instead I see them coexisting (if indeed an R7 etc materializes).
The industry was already facing massive pressures - just anecdotally I fairly regularly walk past a large photography equipment retailer - lately I haven't seen one single customer in there .......