IMO there is no question that Serena will make a cameo in the sun and moon anime. the creators of the anime know that it can only do good for the anime. honestly, they would be shooting themselves in the foot if the didn't. first off, is one of the most(if not the most) popular pokegirls to date, and not giving her a cameo would upset alot of people. The reason that iris didn't get a cameo was honestly because no one liked/cared about her, and giving her a few episodes would present little financial gain. now as to whether or not serena will become a permanent part of the cast, well i dont think so. if serena was going to be part of the sun and moon cast, then dont you think they would of announced it already? or at least alluded to it? the only reason why they wouldn't do this is if she is not going, as intentionally misleading the fanbase is also shooting themselves in the foot.