Under that scenario, Microsoft would offer the Office iOS apps free of charge; those apps, however, would only work, or do more than allow document viewing and reading, when logged in with an active Office 365 account.
That, too, is not new. In fact, earlier this week Google launched an iPhone version of its Quickoffice on the App Store. Quickoffice for the iPhone, and the already-available version for the iPad, are free downloads but require a Google Apps for Business account.
Google sells those accounts separately on its website, not in the Quickoffice apps. Microsoft would presumably do the same.
"Any time there is an opportunity to make more money, Apple wants to be part of that," said Miller. "If we see Office, we'll see much the same thing. Apple will want its part. So Microsoft will have to be careful about how they couch any upsell opportunity [in Office on iOS]."
In practice, that will mean the iOS Office apps won't include a link to subscription renewals, or include account management controls that mention renewals or additional storage purchasing.
Some saw the upgrade of SkyDrive as an even stronger omen of the launch of Office for the iPad and iPhone. Ed Bott, a long-time Windows watcher and ZDNet blogger, was one. "Having a robust SkyDrive app that works with all iOS devices is a prerequisite for a subscription-based Office app for iOS," he wrote Wednesday.
Bott has a point. The newest Office, whether perpetually-licensed, stand-alone versions that run on Windows PCs or those installed locally as part of an Office 365 subscription, defaults to the cloud service for saving files. Unless Microsoft was to do a volte-face on a core strategy, an upgraded SkyDrive must be in place by the time Office appears on iOS.
SkyDrive 3.0 for iOS can be downloaded from Apple's App Store. It requires iOS 5 or later, and runs on the iPhone, iPad and iPod Touch. Microsoft said it was optimized for the iPhone 5.
Gregg Keizer covers Microsoft, security issues, Apple, Web browsers and general technology breaking news for Computerworld. Follow Gregg on Twitter at @gkeizer, on Google+ or subscribe to Gregg's RSS feed. His email address is firstname.lastname@example.org.