Ultimate skin?

It's been over a year since Spirit Guard Udyr was released and we still have no clue about the next ultimate skin. Although it's confirmed there is one in development nobody knows for who or when it will be released. I had some RP in case it was released in October-November, but the unexpected Reaper Soraka got me spending... Whatdo you guys think? Any hints or weird pbe files you have found or even specualtion about who is getting the skin? I personally have no idea...