Microsoft: We can update Office-by-subscription every 90 days

"I can see them adding little missing links where the cloud is different from what's on premises," said Miller. "And then at some point, we'll start to see them building software to improve the service."

He envisioned the updates as rolling out changes to, say, Word one quarter, perhaps to Excel in another.

Microsoft has not been forthcoming on that front, either, although officials have repeatedly mentioned "new features" without citing examples.

"If we add new features to it, we can just change the images on our servers," said DelBene this week of Office 2013 subscriptions. "We will actually just stream to you the differences...between the image you have today, and the image that we have on our servers."

Microsoft may be keeping a tight lid on plans for fear of promising more than it can, or will, deliver. If so, it learned a lesson from Windows Vista Ultimate, a top-of-the-line consumer version that Microsoft pledged would receive regular updates with exclusive new features. Instead, Microsoft stiffed Ultimate owners and then quietly discarded the concept.

DelBene also trotted out an out-of-favor phrase to describe the Office updates.

"I think it will get us to a point where we have a major-minor cadence, because there are some investments that have to happen that require a great deal of forward investment," DelBene said Tuesday. "When you're structurally changing the underpinnings of Exchange, or SharePoint, or the Office applications, those take a while to develop. And so I think we'll get into the short cycle where we can add more features, but then we'll have a longer cycle where we really have to intensively change underpinnings of the services."

"Major-minor" was once used by Microsoft to describe alternating releases of Windows, but the term has gone unused for years. "They would say that, but then they would say that every release is major," said Silver about Microsoft. "Here, they're implying that some updates will be new features here and there, and others will be more aggressive changes. But with a 20-year-old product that's so mature, I can't think of really aggressive changes that they might make every year."

In other words, users shouldn't expect an Office 2014 or Office 2015, but small-step changes to Office 2013 over the next three years.

But even those will mark a major change in how Microsoft works on Office. And while some customers may relish frequent updates and upgrades, others will certainly not.

"There are a lot of organizations that are not used to that pace, and cannot keep up with that quick a cadence," said Silver.

In an interview this week, Paul DeGroot of Pica Communications, and an expert in Microsoft's licensing practices, said that it often takes enterprises three years or longer to migrate their machines to a new edition of Office, and because of that, they often skip one or even two of the following upgrades.