they could e.g. claim that using their 6 ability scores to represent a chars abilities is copyrighted, and lose that (they probably would, if they did). That their chromatic and metallic dragons with their specific colors and breath weapons are copyrighted, and lose that (less clear, I lean towards no, but ultimately no one knows and IANAL).that sound intresting... could you give an example? What could they lose (other then the OGL becoming permanent non revocable)?
Each one is independently evaluated, and whatever they lose, everyone can use, whatever they win, no one can. Ultimately we get a much clearer picture of what WotC actually has copyright of and what is just generic stuff that everyone can use because it is too broad / too generic, like HP, Armor Class, classes, races, levels, ... they might end up holding an almost empty bag. This could essentially decide that other than their IP, they actually own nothing at all (very unlikely however).