I don't think it's that complicated. If I release software under the gpl and to someone to integrate in a closed source application. You don't have gpl code in

I don't think it's that complicated. If I release software under the gpl and to someone to integrate in a closed source application. You don't have gpl code in a closed source application. You have code with 2 licenses. This is perfectly ok, the two pieces of software can coexist. This would be the same, if correctly structured. The only nit would be that code would be forever dual licenced. Some evil company could buy up the code base and do whatever they want and not release code back for 2 years.