The contributed code under Apache would be like any other permissively-licensed third party dependencies used in any proprietary product; you add a copyright no

The contributed code under Apache would be like any other permissively-licensed third party dependencies used in any proprietary product; you add a copyright notice and possibly link to a copy (a courtesy, not even necessary), done. There’s no devil in the details. The entire codebase can be taken proprietary right now and there’s not a thing you can do. You’re free to extend the last permissively licensed version.