A visual designer for Xbox seems to be working on a new project called the ‘Xbox NeXt’ this was revealed on his LinkedIn profile.  The designer has been working on Xbox since 2008. You can see the picture here:

This is most likely a project name in case something leaks out like this. It seems likely that an upgraded Xbox One will be possible with rumors about Sony making a PS4K or a Playstation 4.5 and with Nintendo coming out with a new console which could possibly be more powerful.
This is what Phil has to say about these rumors
“I don’t know anything about any of the [PS4K] rumours that are out there,” he said, “but I can understand other teams’ motivations to do that. For us, our box is doing well. It performs, it’s reliable, the servers are doing well. If we’re going to go forward with anything, like I said, I want it to be a really substantial change for people – an upgrade.”
I’d expect an official announcement at E3 this year.
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