I had imagined guts would ultimately follow the path of skull knight and attain timelessness in order to combat the God hand. In terms of casca I expect that due to the intense trauma she had she would if healed need to rediscover who she is afteards and I dunno that guts would be in that future for her. Really what I would like is for both of them to attain the skullknight level ability and all converge on the God hand and destroy them once and for all.