Microsoft's rumored Surface Phone, the replacement for its disastrous Windows Phone line, is rumored to be one year away. The April 2017 launch is expected to coincide with Redstone 2, the second major upgrade to Windows 10 for PC and mobile.

The source of the rumors is Windows Central, which has been quite tenacious in pursuing this story. It notes a big gap between the quality of the Surface tablet and Lunia 950 phones, both launched last year, with glowing reviews for the tablet and thumbs-down for Lumia. The result has been dismal sales, just 23 million phones sold in FY 2016.

The delay isn't hardware-related. It comes from Microsoft waiting to finish Redstone 2, the follow-up to Redstone, its first major overhaul of Windows 10. Redstone 1 is believed to be the Windows 10 Anniversary Update. A beta went live last week with a bunch of new features.

Because Redstone is such a hefty update, don't expect a follow-up to come any time soon. The bigger the update, the more time they need. So, it would make sense that Redstone 2 would come in 2017. Windows Central said that it and Redstone 3, which hasn't been mentioned at all, would both be heavily focused on "innovation around mobile phones."

That matches Windows chief Terry Myerson's comments at Build last month that Windows Phone was not a focus for the company this year, hence no discussion at the conference.

Two areas of focus

Windows Central says Microsoft plans to focus on two areas: make the most secure phone in the world and make the best phone for productivity.

In the first case, Windows Phone is already pretty secure. You don't hear about rampant vulnerabilities like in Android or about malware. Then again, malware writers don't target platforms that have less than 2 percent market share. In the second case, Microsoft has been trying to make Windows Phone a productivity device with support for Microsoft products. So, that makes sense.

Windows Phone sales have cratered. I'm not sure there will be any potential market, even with nifty features such as Continuum for running Win32 apps on a smartphone, left for Microsoft to grab. It's a shame because in many ways, Windows Phone is a superior operating system now to its competitors. But the whole thing has been bungled, and I have never seen a product left for dead like this come back in any significant way.