Having gone through multiple "due diligence" lawyer passes on tech licensing, I am not sure that this would fly. Having every contributor hold an individual copyright with no agreement in place seems like an easy, but problematic solution. I don't see really any other examples of this in the wild, other than code copyrighted by a "foundation" which is a formal entity. I think I understand the intent, and I think it totally works for a "pet project", but do you see a problem here?
How about you having the copyright?
- Josh