I do hope some bot out there is collecting and archiving Flickr's creative commons photos before they disappear for good.
It's not a like-for-like replacement, but GBIF (my employer) indexes a fairly large collection now. You need a scientific (Latin) name for an effective search.
HN's favourite genera are presumably these three: https://www.gbif.org/occurrence/gallery?media_type=StillImag...
NB the "license" filter applies to the text parts of the record, many images have a different license.
Of course Flickr are going to find metrics that make this move sound low impact. But are these total accounts made up of mainly dead useless signups from over the years? If the 3% of users are of small significance, then I suspect Flicker wouldn't bother with this update.