Patrick Moorhead, an analyst at Moor Insights & Strategy, said that what Microsoft needs more than a unified OS is a unified development environment, which he expects will emerge in the next 18 months. "A unified Windows OS risks being a light PC OS and too heavy for phones," he said.
Rob Enderle, an analyst at Enderle Group, said that with software virtualization, Microsoft potentially doesn't have to create a "one-size-fits all" OS. However, he said Microsoft seems to be on a path over the next five years of using an embedded core for all platforms where developers would add user interfaces that work best for a certain screen size.
Insights from Windows developers
Whether Microsoft's operating systems fully come together was the subject of some debate among four developers who were interviewed separately by phone and email. However, all four support a fuller common development environment across all the platforms.
James Vertisan, CEO of Vertisan Inc., a maker of golf-related apps, said it is "imperative to merge" Windows, Windows RT and Windows Phone, and he commended Microsoft for already offering a shared code base between the OSs.
He estimated about 75 percent of the source code is already in common. "There are things we can't re-use across platforms, such as the layout of a particular view, but everything else that lives beneath is synonymous," Vertisan said. A phone is primarily navigated vertically and displayed at 800 x 600 pixels, while a tablet, displayed at 1366 x 768, is navigated primarily horizontally.
Vertisan makes the Shotly golf app for Windows Phone 7 and 8 and iOS, and is about to release a social networking app for golfers called Golfly, which is being showcased on Windows 8 devices. It will allow users with a tablet to remotely follow someone playing golf, picking up their inputs on shots from a smartphone running Shotly, with the ability to interact and send text messages, such as "Great shot!" Both Shotly and Golfly are free apps, although in-app purchasing and upgrades are available.
Vertisan sees a chance for Windows Phone and Windows tablets to grow in market share, partly because of the ease of development of apps. He said he and other developers have seen efficiencies in using Microsoft's C# and XAML programming languages in building apps for Windows.
"The base core of the OSs is coming together and that's a good thing to help speed to market of apps ... but to a certain extent the operating systems need to remain a little bit separate," added Atley Hunter, a developer of Windows Phone and Windows 8 apps.
"Moving Windows Phone to the full Windows kernel made a big difference in device management, security and hardware support, [which] allowed the development platform to grow closer together allowing increased code re-use," added Tom Verheoff, a partner for Methyllium, which recently built the Windows 8 hotel booking app for Booking.com.
"Really unifying the [three] platforms into one Windows development environment would be a big improvement for the developer experience. Windows Phone 8 already allows reusing big parts of an app's codebase, but reusing even more would allow developers to save time and money," Verheoff said.
Creating a single, unified development environment for all the OSs "should definitely be a high priority" for Microsoft, Verhoeff added. Doing so would "make the life of every developer on the platform a lot easier and grow the addressable user base."