Personally I've evolved into supporting free culture licensing only. Essentially having a CC-SA/CC-BY-SA (dropping out the NC) license is giving you a free culture license. There's no real reason to force the NC part in - it's just asking for trouble. Having a world is fine and dandy but if the individual licensing of maps/whatnot prohibits it's commercialization in the future, it's a damn sure thing CWBP will never evolve into an actual gaming product but remains a niche side project of hobbyists and professionals of the gaming industry.