She wouldn't get anything too reddish I believe, since she'll most probably be in front, next to Riho, and we can have 2 reds next to each other ... Unless Riho gets a color change, which seems unlikely, many fans would cry foul
Well, a few members stated, during the event where they all wore yukata, that Sakura would be in white until her color was decided. So I think it's just white until she has an official announcement for her color, which will be right before or during the Winter concert more than likely.