The Russian super-leaker
Wzor, who by the way is uncannily correct in his predictions, has pegged announcements on both operating systems coming on July 13-17 at the Worldwide Partner Conference.
The first tweet goes like this: "Windows 8.1 Update 2 will be announced during Microsoft WPC 2014 July 13-17 Win 9 beta will be probably presented same time. by WZT" And the second: "JUNE 06/26/14, WINDOWS 8.1 UPDATE 2 RTM Build sign-OFF is more likely occurring now! by WZT"
Update 2 probably won't have a desktop Start menu or a Modern-Mix style capability for running Metro apps inside resizable windows on the desktop. Instead, most bets emphasize plumbing changes in Update 2 and very little if anything on the UI side.