Hey Klaas,
I’m currently still using the old Sketchfab viewer. As far as I know, Sketchfab will continue to stay online, so the backup version of the screenshot viewer is sufficient for me at the moment. However, I do hope that Fab.com will soon have a screenshot viewer or something similar, so my team and I can continue exporting screenshots from the models. This feature was extremely helpful on Sketchfab.
Thanks again for all your help!
Cheers!