Microsoft is going to release a second update for Windows 8.1 this month on August 12 but don't expect it to include any major features or to be mandatory. It will include some minor design changes and it won't be mandatory, unlike the first Windows 8.1 update.
Microsoft's original plan was to make this update a much bigger with a new "mini" Start Menu according to Mary Jo Foley. But the team scrapped that plan a couple of months ago, deciding instead to make the new Start Menu a feature of Windows Threshold (codename) which is likely to be called Windows 9, is still sounding like a Spring 2015 deliverable.
Source: ZDNet