The 5Fans forum now has a board just for the upcoming Rockchip 3288-based iFive Mini 4 [Google Translate].
And the first post gives some details of the new model [Google Translate]:
• The back camera will indeed be upgraded from 5MP to 8MP
• It will have WiFi a/c (MIMO?)
• The back will still be all-metal
• No release date yet; software being debugged