Let's create a tool to help compare license compatibility for derviatives. Shouldn't be that hard now that all licenses has these metatdata tag on them. Only need a database with which licenses are compatible with which licenses (and versions) and a nice UI.
https://commons.wikimedia.org/wiki/Commons:DerivativeFX
http://wayback.archive.org/web/20140218133122/http://toolserver.org/~luxo/derivativeFX/deri1.php
https://commons.wikimedia.org/wiki/Commons_talk:Upload#future_of_derivativeFX
https://meta.wikimedia.org/wiki/Requests_for_comment/Abandoned_Labs_tools
Proposed in Community-Wishlist-Survey-2016. Received 34 support votes, ranked #43 out of 265 proposals. View full proposal with discussion and votes here.