[thekingofh]

Then someone can dual license the code. Something like AGPL for general development and commercial licenses via request. This way the source is open at all times and companies that want to use it and modify it for commercial purposes can get a commercial license for that. In this case the biggest issue is copyright assignment. In order to dual license you require everyone who's contributed to agree. In large projects that's difficult. In a company, copyright can be handed over to the company, but anyone outside the company who contributes has to either sign over copyright or agree to letting their contributions be dual licensed.

The best option looks like a tight copyleft license combined with a contract for copyright assignment and revenue sharing for contributors and dual licensed for commercial use. The most difficult part of this would be gauging developer worth based on contributions, but that's something that happens in every company anyways.