Sure. Here's a transcript of the earnings call. (You may need to register to read it.)
Nadella does say, early on in his prepared comments, that, "We will streamline the next version of Windows from three operating systems into one single converged operating system for screens of all sizes."
Later during the Q&A session, however, he was asked about how this "one version for all devices" would change the number of Windows SKUs that are available, and he said this:
Yes. My statement Heather was more to do with just even the engineering approach. The reality is that we actually did not have one Windows; we had multiple Windows operating systems inside of Microsoft. We had one for phone, one for tablets and PCs, one for Xbox, one for even embedded. So we had many, many of these efforts. So now we have one team with the layered architecture that enables us to in fact one for developers bring that collective opportunity with one store, one commerce system, one discoverability mechanism. It also allows us to scale the UI across all screen sizes; it allows us to create this notion of universal Windows apps and being coherent there.
So that’s what more I was referencing and our SKU strategy will remain by segment, we will have multiple SKUs for enterprises, we will have for OEM, we will have for end-users. And so we will – be disclosing and talking about our SKUs as we get further along, but this my statement was more to do with how we are bringing teams together to approach Windows as one ecosystem very differently than we ourselves have done in the past.
Lots of hedging in there. You don't need a single, converged OS to give developers "one store, one commerce system, one discoverability system." Those are all ancillary functions. A "team with the layered architecture" doesn't sound like every version of Windows is going to share the same layers. And clearly nothing about Windows is going to be simplified from the customer's perspective; there will still be six or eight SKUs, with each offering different benefits.
Rather, I take Nadella's comments to mean he's streamlining the OS engineering group so that the people working on each Windows platform work in tandem with the others and they all have similar goals, milestones, etc (good).
I also take it to mean that Microsoft will offer developers who are building so-called Modern apps a common set of APIs that will be available on the various form factors, so they eventually should only have to write their apps once and they will run on every kind of device. That sounds OK, but it's only going to be true for Windows Store apps -- and to achieve that, you don't need every device to be running an identical OS.
In other words, no Holy Grail here, but Microsoft is streamlining and rationalizing its OS engineering efforts, which makes good sense at this juncture.