Players who long for the precision of mouse and keyboard support on Xbox, your wishes are (possibly) coming true.
During a Build 2017 presentation (Build being an annual Microsoft-centered conference) a Microsoft senior official said that soon, game developers who are part of the Xbox Live Creators Program will be able to turn on all Windows functions.
And yes, that includes mouse and keyboard support.
There's no telling when (if ever) this feature will make it to the everyday console owner, but at least the groundwork is being laid. And hey, while this may only be available to those who are a part of Xbox Live Creators Program in the near future, it's pretty dang easy to get enrolled. And if you need some suggestions on how to actually make a game, might I suggest this guide on, well, how to make your own games?