Apparently Microsoft didn't let everyone in on the fact that they are developing a new console, at least according to Final Fantasy XV Director Hajime Tabata. In an interview with Kotaku, Tabata discusses a variety of things Final Fantasy related, namely optimization. He revealed that not only had the development team not started working on the next evolution of hardware, he hadn't even heard of it.
He said:
"No, we haven’t started anything… I first learned about Scorpio at the [Microsoft] conference. I was there waiting in the green room and I go 'ooh wow, what’s that?'"
I suppose that is understandable when you are a Game Developer. Considering the massive amount of hours that Tabata and the team have had to be pouring into the ten-year-old project, just to get something out, you can definitely see how they might have missed the unrelated rumors from around the internet.
Tabata goes on to say that he would like to be able to get Final Fantasy XV running in 4K, but acknowledged that he would have to "get a real feeling of what it can do and grasp it."
It's also worth mentioning that Tabata later says that the Xbox One version of Final Fantasy XV is expected to be 900p while the PS4 version will be "full power" (presumably 1080p), with both at 30 FPS.
Source: [Kotaku]