Long-term or not, Miller isn't enthusiastic about Windows RT's chances. "I've been concerned about Windows RT from the beginning," he said. "I don't see a long-term viability for Windows RT as a value-driven strategy."
While Windows RT has languished -- according to IDC, Microsoft and its hardware partners shipped 200,000 Windows RT devices in the first quarter -- Windows 8 tablets have gotten some sales traction, and more importantly, support from OEMs. IDC estimated first-quarter shipments of Windows 8 tablets at 1.6 million units.
Acer, for example, recently said it would wait until Windows Blue before deciding whether to build tablets running Windows RT. Meanwhile, it's keen on Windows 8 tablets, as a leak of an 8.1-in. Acer Iconia tablet last week showed, even though its $380 price is higher than that of the entry-level iPad Mini.
"This says that OEMs believe customers would rather have application compatibility than hardware efficiency," said Miller, contrasting battery life between devices running ARM processors and Windows RT against others powered by Intel CPUs and Windows 8.
"And as [Intel's] Atom moves down market, for the same cost [as ARM] it will provide better power efficiency. That will threaten Windows RT on an ARM processor," Miller said.
O'Donnell countered, saying that Windows RT -- designed to run on processors created by Nvidia and Qualcomm under their ARM licenses -- was important strategically to Microsoft. "There's some validity to the strategy, because a lot of the future is in ARM," he said, citing IDC's estimates that 75% of tablets will be powered by ARM, with the rest relying on Intel's x86 architecture.
O'Donnell would have liked to see Microsoft make what he called a "clean break" from Windows with RT, including giving it a different name to make it clear the tile-based OS wouldn't run older Windows software. But Microsoft took a different path.
"Microsoft might have to show the way, like it did with the Surface, for Windows RT from a content perspective," said Milanesi, referring to a smaller, less-expensive tablet running the lighter-weight operating system. "They need to show the way where they want RT to go, because as it is now, it's all very confused."
Patrick Moorhead, principal analyst at Moor Insights & Strategy, was of the same mind. "I'd like to see some candor," he said of Microsoft's plans for Windows RT.