This is nuts, I would have never guessed you could swap an entire OS out! I scanned the code, this can be done without rebooting and while preserving "uptime" yes?
reboot # And pray it'll boot.
My success rate with such projects is sufficiently low that I only attempt it when I have no other option. And that's for Debian -> Debian bootstrapping. Most of the time I manage to fumble a crucial parameter and the boot fails. I wouldn't even think of doing this remotely except as a challenge.
But that's not to mean you shouldn't try it for the fun of it!
Is there any actual utility to scripting such a thing? I'm a strange person who enjoys distro-hopping and setting up PXE servers and such, so it seems like something I'd try.