Microsoft today confirmed reports that it plans to complete the development of Windows 8.1, a major update for both Windows 8 and Windows RT, in August. New devices preloaded with the update will be available in time for the holidays.

Microsoft had originally planned to finalize Windows 8.1 on August 1 (8/1), according to my sources—a milestone still known as “release to manufacturing” (RTM). But I learned a few weeks ago that this schedule had been pushed back a few weeks. Microsoft on Monday confirmed this news, with Windows CMO and CFO Tami Reller stating that PC makers would receive the final version of Windows 8.1 integrated with Windows 8 and Windows RT in late August.

But while the world anxiously awaits the Windows 8.1 update, sales of the current version of Windows 8/Windows RT has stalled. Reller reiterated Microsoft’s previous announcement about the firm selling 100 million Windows 8 licenses, but that milestone happened back in May. She said that “new customer activations [of Windows 8] continues at a consistent pace”, which isn’t good: As I noted previously, this suggests that Windows 8 is selling at a rate of less than 14 million licenses per month, far below the 20 million per month average obtained by its predecessor, Windows 7.

Reller also noted that there are 20 million enterprise evaluations and that Windows 8 has logged 60 billion hours of use since its release last October. It’s hard to compare these numbers to anything.

Originally seen as a minor polishing of an OS that no one seems to want, it’s pretty clear now that Windows 8.1 represents a major do-over, or mulligan, for Windows 8 and Windows RT. Indeed, this release, comprised as it is mostly of small fixes, is now incommensurately important to the future of the franchise. Fortunately, Microsoft seems to have struck the right balance with Windows 8.1, and as you can read in my growing series of Hands-On with Windows 8.1 articles and other posts on the SuperSite for Windows, a major comeback is in the making.