Windows 8.1 Update 2 is inches away from being finalized. We're expecting the update to hit RTM within the next week or so, which means the update will be ready in-time for one of Microsoft's Patch Tuesdays in August. According to a number of sources though, Microsoft aren't planning to make too much of a fuss about Windows 8.1 Update 2, and instead may opt to push it silently without any announcement.
The reason Microsoft may opt to push the update without an announcement is because Update 2 doesn't include much on the consumer side of things. It's mostly under the hood, bar a few UI tweaks. Users who are expecting to see vast changes to Windows 8.1 with Update 2 are in for a disappointing time.
Update 2 was originally set to include the new Mini Start, but Microsoft decided that it was best to save what is probably one of Windows biggest features for it's major launch with Windows 9 next year. Microsoft even demoed the Mini Start running on a build of Windows 8.1 Update 2, which is evidence towards Microsoft's original plan of launching the new Mini Start this August.
It's possible that Microsoft, if they do opt to announce Update 2, will talk about it in detail at its annual Worldwide Partner Conference in July, however it's also possible that Microsoft will decide to talk more about Windows Threshold instead. Information about this is scarce at this current time, so as per usual we must ask you to take everything here with a grain of salt.