When it out
That'll be when Apple decide to release it, basically, know one knows.
As you posted this in the iPad 1 section and you are asking about a version of iOS that won't be available on the iPad 1 I'll move this to a better area of the forum for you.
Probably sometime between today and the year 3000 A.D.
Current Apple Devices:
iPod Touch 4th Gen-Black-8G-WiFi