I wonder how they will approach lenses going forward.
Assuming the rumor is true and Canon really do produce a BSI APS-C EOS R camera, they possibly might only need to produce a kit lens that covers something close to the traditional range of 18-55mm (28.8-88mm full frame equivalent), and perhaps something a bit wider, like the old 10-18mm EF-S lens.
I would speculate that the range of lower end budget build lenses released or coming soon would cover most requirements.
- RF 16mm f/2.8 = 25.6mm on APSC
- RF 35mm F/1.8 = 56mm on APSC
- RF 50mm f/1.8 = 80mm on APSC
- RF 85mm f/2 = 136mm on APSC
- RF 100-400 f/5.6-8 = 160-640mm on APSC
- RF 600mm f/11 = 960mm on APSC
- RF 800mm f/11 = 1,280mm on APSC
These lenses would provide equivalents to the popular sizes of 24mm, 50mm, 85mm and 135mm in prime lenses on a crop sensor body, and quite a bit of the long telephoto range from 160-1,280mm with the rest of the primes and zooms.
It wouldn't be the first time that APSC users have used full frame budget Canon lenses, the legendary nifty-fifty EF 50m f/1.8 STM was full frame glass after all, Canon never produced a 50mm EF-S lens, the closest was the 60mm EF-S Macro,
This is a purely speculative minimalist option that Canon may take, or they might not and produce a swag of budget crop lenses. It depends on what the market wants / what will sell, or what the sales strategy is, neither of which we know anything about.