We know Windows 10 will arrive on the desktop later this year, but server-side updates aren't coming quite as quickly. The next version of Windows Server isn't going to appear until 2016.
Microsoft outlined its broad plans for Windows Server in a blog post late last week. This is the most significant paragraph:
As we continue to advance the development of these products, we plan to release further previews through the remainder of 2015, with the final release in 2016. Our next preview is planned for the spring of 2015. Windows Server will continue to share the same core technology as Windows and we will continue working together on solutions for our customers.
This is noteworthy for two related reasons. Firstly, It means that Windows Server releases won't be in sync with the desktop edition. Microsoft launched a technical preview for Windows Server last October, at the same time as the main Windows 10 preview. While it hasn't yet specified an official release date for Windows 10 on the desktop, it's widely assumed that it will appear sometime in the third calendar quarter of 2015, in time for new machines to go on sale for the Christmas market.
More particularly, it means that Microsoft has at least partially abandoned a pledge it made back in 2013 that Windows Server would be on a sped-up update cycle, with updates to be expected as frequently as yearly. That always seemed ambitious, and now it seems to have been scaled back.
What might it be called? That's hard to tell. Office 2016 is going to be released this year, but will have the 2016 branding. Microsoft may well elect to stick with the Windows 10 branding, which doesn't tie it to a particular year.
One key question is how Microsoft plans to charge for the new version. Updates to Windows 10 on the desktop are going to be free, but we're unlikely to see the same approach for Windows Server — it's a major source of profit for Microsoft.
Last year, Microsoft hinted that it might change the charging model for some of its data centre editions, giving customers the choice between paying for more rapid updates or instead settling for a steadier release cycle. That makes sense in a data centre environment, where many of the updates are likely to draw on development work being done for Azure. But it would be a harder path to pursue for Windows Server more generally — especially if the pace of updating is slowing.
There's one other obvious reason for Microsoft to hold back on updating Windows Server this year. Windows Server 2003 reaches the end of its extended support lifecycle in July this year, forcing those users to migrate to a new version. The next version won't be out at that point, and migrating users might be disappointed to move to the current release only to see it "out of date". From that perspective, a delay makes sense.
The next major milestone for Windows Server will be Ignite, the "TechEd on steroids" conference Microsoft is running in Chicago in May. We'd expect to see a new preview release by then.