FurAffinity is back up and unsurprisingly the cause was
their shit tier database code, and their fix is to purge unread notifications older than a year.
FurAffinity is to furry art sites what someone like DSP is to lolcows. There have been jokes both here and outside the farms about how DSP manages to outlive other content creators and lolcows somehow after things that should have killed his career (the fapping incident comes to mind). FurAffinity is the same way, not even a source code leak or password dump that ended up on haveibeenpwned could make the site become irrelevant.
A new furry site would have to both gain acceptance with ever more critical furries and become the same "commission hub" that FurAffinity became known for. Lots of furries make accounts there just to browse art and commission art especially if they're not a fan of the "art in between 20 orange man bad posts" model that Twitter is known for. Even if FurAffinity lacks features and is held together with tape, it's one of the few mainstream community focused furry art sites (and arguably adult art sites in general considering how it has plane porn and the like).