I'm not sure I agree that Canon wouldn't re-launch lenses in APS-C RF mount - it really depends on their long-term plan
The long term plan is simple. APS-C will remain for entry-level cameras and the 7D market will be moved onto higher resolution FF cameras that can crop down to a decent resolution at APS-C (ie 50mpx+ sensor). Sure, there's a big price differential at the moment, but that price gap is going to shrink over time.
There won't be a need for APS-C lenses on the RF mount. The R7 is likely a one-off APS-C body for the RF mount, I doubt there will be an R7 Mark II. There won't be a need.
Even in 2 years time the R5 is going to be cheap enough that potential R7 buyers are going to have a hard think about whether the R5 is going to be better for their needs.
Yes, it won't be ideal for everyone. But the camera market is shrinking, and Canon have less flexibility to produce individual bodies (and entire ranges of lenses) for a single submarket.
I could be entirely wrong on this - but let's see what happens...