According to Neowin's Brad Sams, Windows 10 is on target for a June RTM date.
That's an aggressive schedule, leaving only about four more months of development time for a major OS release that is still missing key parts.
But that deadline says as much about the new reality of Windows development as it does about the status of Windows 10.
RTM used to stand for "released to manufacturing," and it was a very big deal, marking an end to further feature development and the beginning of a process that ended up with shiny disks in shrink-wrapped boxes.
These days RTM means "released to manufacturers," and it isn't so much an end as it is yet another milestone.
In the modern era, declaring an RTM milestone doesn't mean "We're finished." The days of monolithic Windows releases, with features frozen in Carbonite, are long gone. Instead, reaching the RTM milestone has a multitude of meanings for different audiences.
"We're done experimenting with the user interface ... for now."
The release of frequent technical previews means that designers and developers can get feedback from beta testers as they tinker with the user experience. There's likely to be lots of that tinkering between now and June (or July, if the June deadline turns out to be overly optimistic). An RTM release means documentation can be written and trainers can begin preparing courses with reasonable confidence that the user experience is nailed down.
"There's still a lot of work to be done with apps."
One of the most underappreciated changes introduced beginning with Windows 8 is the shift of features from the operating system itself to apps, which can be delivered independently through the Windows Store instead of through Windows Update. This week, for example, the new Photos app got a significant update, in between preview releases. The new unified communications client (Mail/People/Calendar) will also ship as an app.
Shifting features from the OS core to apps means that a delay in one feature doesn't have to delay the entire product's release. Microsoft has already decoupled one major feature, the new OneDrive sync client, from Windows 10 itself. Some features, the company says, "will make it into the first release ... However, others will come in updates that follow later in the calendar year."
"OEMs, you may ship your hardware when ready."
A June RTM milestone gives hardware makers plenty of time to integrate the new OS into PCs, tablets, hybrid devices, and phones, with a realistic chance of having them ready for back-to-school and holiday promotions. One of those OEMs is Microsoft itself, which will almost certainly release a new version of the Surface Pro running Windows 10.
"The general public won't get Windows 10 until months after the RTM release."
If you've signed up for the Windows Insider program, you already know that you can move a slider to determine how often you receive preview releases. Choose Fast to get the latest code as soon as it's out, choose Slow to let others be the Guinea pigs. The June milestone will, presumably, be a public preview, to be followed by several more preview releases before Windows 10 is offered as a free update to the general public in the fall.
"This marks a long-term support release."
For corporate customers with large enterprise deployments, committing to a new OS is a very big deal, and the idea of continuously delivering new features and updates is a nonstarter. To serve those customers, Microsoft announced last month that it would provide Long Term Servicing branches for Windows 10:
On these branches, customer devices will receive the level of enterprise support expected for the mission critical systems, keeping systems more secure with the latest security and critical updates, while minimizing change by not delivering new features for the duration of mainstream (five years) and extended support (five years).
An RTM date in June actually starts another countdown to an even more important date: the General Availability milestone, which will probably be in October. That date will mark the beginning of a major marketing push from Microsoft and its hardware partners. More importantly, it will start the one-year clock on Microsoft's free Windows 10 upgrade offer for consumers and small businesses running Windows 7 and 8.1.