Haha, exact same thing happened to me a couple weeks ago. You probably had the same issue as me. The driver dropped support for older cards and you had to switch to a legacy AUR package. I fixed it with some frantic googling while my friends waited a half hour. Not sure how you would know this without subscribing to some arch news feed or something. Not ideal.

That's exactly how it's supposed to work: Arch expects you to check the notes on their news section always before you update. The NVIDIA driver issue and solution was posted on Dec 20th.

I'm not saying I'm reading these regularly, just that yes it's the expected way.