Board Thread:Questions and Answers/@comment-31614123-20170327194546/@comment-30827145-20170327212406

Only bandai knows. But they already gave one for luffy and one for zoro or nami. They might celebrate the other 5+ strawhats by giving one skull. But I wouldn't expect more. And to answer "when', nobody knows but probably not in a near futur as the characters are also new on japan version.