Keep using it and you'll fail to boot after an update, it's just a matter of time. I've had it happen even on devices I exclusively used for browsing and playing videos.
You make it sound like you should keep a bucket of water handy before you even boot it up.
No, but you should keep an arch thumb drive handy whenever you're updating. You never know when the installation script will give up, or GRUB release a faulty update.