In the past, Canon released EF lenses into the market. Then Canon killed all 42mm flange focal length lenses, R/FL/FD and FDn completed. All professional photographers had to sell their priceless lenses and pulled extra money from their pockets to purchase EF lenses for EOS cameras. There were very angry photographers at that time.
Then Canon provided a special kit, 1.26x four elements adapters to allow work with ONLY to long telephoto lenses. It remains incompatible with a fisheye to short telephoto. The kit sold from Canon only not through any retail stores. It was short-lived because the pictures degraded by the kit.
Now, Canon repeated the same behavior with new RF lenses. Now, Canon will kill all EF lenses and force everyone to use RF lenses someday.
The problem with Canon was greedy and made a windfall profit from victims. Kudos to Nikon for effort compatible with their F lenses.
I do not trust Canon for their manipulate the schemes as they did in 1989 incident. The best way for everyone not to buy any Canon mirrorless cameras and RF lenses until Canon realize this situation and will correct themselves remain with EF and find a way to make compatible with FD or previous lenses.