Sure, "copy-center" attitudes like those common in BSD communities would have prevailed, likely, and we'd have entered the shared-source/commons-licensing phase

Sure, "copy-center" attitudes like those common in BSD communities would have prevailed, likely, and we'd have entered the shared-source/commons-licensing phase a decade earlier. Without the option of copyleft, an entire pillar of philosophy would be missing, but it likely would not matter, since the world would still be just as corporatist. The main thing missing in that world would be a belief that copyright can and will be changed in order to better suit the people.