Breakdown realistically, and you'll see why it's unlikely. Let's be honest: Xbone has had a rough generation. From being the most hated thing since the last most hated thing, to abandoning virtually every policy and vision, Microsoft have had to work hard to get the customers they have today. And they're so far behind their competitor, they abandoned hardware sales figures as a performance metric. Then, in order to stop the Xbox 360 from slowing down adoption rates and cannibalising future hardware sales, Microsoft implemented an astoundingly generous backwards compatibility system. Microsoft need positive PR and customer-friendly business decisions to salvage every sale possible.
Now, imagine if Microsoft released a revised hardware version of the Xbone that was superior in every way. How do you think the customers that Microsoft have managed to retain would feel about supporting the Xbone thus far? Look at the angry people who felt forced to buy a Kinect, because Microsoft said they'd never sell the Xbone without one. And then they sold the Xbone without one. For less. And that's not even taking into consideration the technical impossibilities, being that changing the fundamentals of a console mid-gen, and expecting old titles to work without issue is... not realistic.
Releasing a superior Xbone at this point would be the Xbone reveal all over again.