I'm disappointed that they haven't enabled the existing hub, but they've taken the approach to add Thread.
Multi-Admin with the controllers is the key piece I'm interested in. Matter Controllers will need to have that extra security @SmartHomePrimer, but I don't think the endpoint devices themselves will be restricted in that way.
My read is that you'll add a Matter device via the QR Code with your chosen Controller (App) - i.e. Google, Amazon, Ikea, whatever, and then that Controller will share that device information with the other controllers. So adding a device to a Google Home controllers will also make that same device available to the Apple Homepod. If that's how it works, then Apple users will be very happy I think.
Authorizing Matter Controllers to work with each other is the bit i'm unsure about.
