As someone interested in eventually making code plugins for the UE marketplace, I am happy with the idea of making the UE glue code available to customers while providing a set of static libraries to isolate proprietary IP. The marketplace could be set up to show which platforms are explicitly supported by a given and if full source was included. Perhaps there would be a “Supported Platforms” list where there would be a box for each platform that said “Source”, “Binary” or “None”. Some devs could provide full source if they wanted to, and those who had reasons not to could still contribute. If the marketplace team were able to build a test framework that could compile, possibly run some tests (stretch goal), and publish the results to the website and directly to each developer for each release (and perhaps daily if a failure occurred) that would be super useful. People could choose to support the developers who met their needs. Seems like a great solution to me!
I’m looking forward to this getting sorted out one way or another. Best of luck!