A hint came to us from Whatshisgame about a possible Princess Candence (the pink alicorn that we have yet to see appear in an episode) toy in the near future. According to this forum post, a pony named StrawberryReef found it in a German toy listing and translated the text to find the date, which says August 2012. Alongside that listing was one for a plastic castle toyset, possibly related.
Hopefully they make this particular run in G4 style and resist the urge to recolor yet more G3.5 stuff. Come on, Hasbro- we will buy this stuff. Impress us!