I'd love to see this in the bootloader, along with a selection of binaries useful for recovery. Might sound silly but over the years I have had many a remote system get to the bootloader and then no further after an upgrade. Nowadays we've usually got a nicely sized EFI partition, why not stuff it all in there? Gimme a full Linux userspace from the bootloader, it would feel luxurious when I'm up at 3 am trying to recover a broken system halfway across the country.
Or is there already a solution to this that I've been missing? (Yeah, KVM/IPMI/etc, I know, but not all hosters make it easy to get to that.)
The solution is "don't apply untested upgrades to critical servers at 3am" :)
If you must do such upgrades, solutions include hot standby hardware, IPMI, an on-site tech with a screen and keyboard, or moving everything to the cloud.
Of course, but all those things (including upgrading during business hours) require budget. So, back to my original question...