I don't get why this is a sticking point. There's no reason to update the Docker CLI independent of the Docker server, and it would be silly to run two versions of Docker on the same host, so why would it matter?
> Each version of the CLI is incompatible with the last version of the CLI.
Sure, but I don't think this is a show stopper. You can and should only carefully upgrade between versions of Docker (and other mission-critical software). The process is functionally identical to the process you'd use to perform a zero-downtime migration between versions of the Linux kernel -- bring up a new server with the version of Docker you want to use, start your services on that new server, stop them on the old server, shut down the old server, done.
I don't mean to suggest this is trivial, only to suggest that it is no more complicated than tasks that you/we are already expected to perform.
It's interesting but it's also already being done, and there is (presumably) also a long list of other upcoming projects being developed by folks with big-money (e.g. NASA, ESA). The question, then, is what might small-money folks do with a satellite like these?
If I remember correctly, Digital Ocean was by far the greatest source of Wordpress pingbacks. They've got a severe problem on their hands. I had submitted a report to their abuse contact weeks (months?) but have not yet heard back.