It's official that the box art Gameguy showed us is the official box art:
http://mynintendonews.com/2013/08/25/heres-the-box-art-for-mario-sonic-at-the-sochi-2014-olympic-winter-games/
http://mynintendonews.com/2013/08/25/heres-the-box-art-for-mario-sonic-at-the-sochi-2014-olympic-winter-games/