Interesting ideas but I wonder if there will be any distribution apart from Red Hat that would really go all the way to implement these ideas. While it seems to solve many security problems, supporting something along these lines seems very aligned with support contracts.
I can see NixOS doing similar things. It's all about declarative configuration.
Also very useful for embedded Linux distros, an A/B setup can help protect against update corruption due to power loss. If one of the two fails to boot, it can try the other, and retry the update.
He says he wants it hackable and secure. I don't think he favors lock-in or throw it away when doesn't work.
The dilemma there seems how do you keep it quickly hackable for yourself but difficult to crack for the bad guys. What are your counterproposals if this is a nightmare?