Honestly I think it’s just D&D messing with us. An artistic way of showing Winter Is Here. Besides there is a pattern of misleading promo trailers, all is not what it seems so I am not taking it too seriously.
Although it did plant the idea of Cersei transitioning into Queen Cersei the White Walker – she does have the heart and temperament for it – however I am guessing (in the show) Daenerys will likely get her hands on Cersei before the Walkers do.
Who knows though …. anything is possible.
A pair of short spikey white frosty horns would hold up her crown ever so nicely 🙂