I'm not too sure of the details, all I know is that some of the plugin creators won't be able to port/update their plugins for C3.
One example is the Box2d+ plugin, I've recently bought to play with. The creator stated that as it is now, he can't support C3 (not sure of the details).
I'm just wondering if this will effect any of the other widely used plugins.
I assume it might have something to do with this thread ...