Probably all future cameras and strobes will use this new hotshoe. This also keeps 3rd party out without use of additional adapters.
Unfortunately that has huge ramifications for studio use. It's one thing to screw over Yongnuo, but Profoto, Broncolor, Elinchrom, etc.?
Okay, going to take a deep breath and hope it's not as bad as it sounds.
Why do I always get the feeling that with the R line the conversations at Canon go something like this:
Engineers: "Hey, we've got a brand new 70-200 lens design that retracts and is super compact."
Marketing: "Great!"
Engineers: "Of course it won't take extenders."
Marketing: "Oh crap!"
Engineers: "Guess what, the new Canon R5 can shoot in 8K."
Marketing: Great!"
Engineers: "Of course it will overheat within minutes and make the camera unusable for hours."
Marketing: "Oh crap!"
Engineers: "We have a new 100-500 lens"
Marketing: "Great! Will it take extenders?"
Engineers: "Yes, but only from 300mm out."
Marketing: "Oh crap!"
Engineers: "We are completely redesigning hotshoes."
Marketing: "Just shoot us now."