You are assuming that they will release a turn-key working product. Its possible for them to just release key parts that are unique. For example: https://github.com/NoelFB/Celeste/tree/master/Source

This game designer only open-sourced his code for the player object. As I am not a seasoned game developer I have enjoyed going through this code and learning some of the techniques.

Maybe Digg can help bring up the next generation based on their techniques. Or maybe it helps foster a discussion around how not to implement something.