You may remember above image posted by Nokia on its official Facebook account. It was a good catch and was bit surprising to see a new Live Tile size in this image. Now seems this large Live Tile is indeed coming with Windows Phone 8.1. Nawzil has posted the below tweet confirming the new Tile Size.
Live Tile sizes in Windows Phone 8.1: Small, Medium, Wide, and Large. #WindowsPhone8.1 #WindowsPhoneBlue — Nawzil (@Nawzil8) February 9, 2014