I have a different perspective. There are millions of chromebooks out there updating all the time, from the firmware to the kernel to the root file system to everything. It all works.
If you are telling me that the upgrade technology of Plan 9 can not handle an automatic upgrade, fine; we have the proof. If you are telling me Plan 9 should not or never will be able to handle an automatic upgrade, and is going to require a heads up email for each kernel change, I have a hard time taking that seriously. This is not a human communication problem. It's a technology problem, trivially solved for many years now by many systems. ron