Where do you get the impression that "a gazillion URLs" broke?

Picasa Web Albums will continue working until the album archive view is ready.

Also, all of the photo from PWA are hosted in Google Photos Backend - and will continue to be hosted there. There are accessible in Google Photos and the URLs will continue to work.

If you haven't seen it, the original blog post has better information than the linked article: http://googlephotos.blogspot.com/2016/02/moving-on-from-pica...