We might be reading too much into it, but it looks like Microsoft's Phil Spencer has just confirmed that the company is planning to add mouse support to Xbox One sometime soon.
Responding to a question on Twitter, Spencer didn't rule out the possibility to stream games from Windows 10 to Xbox One. When told that this would require keyboard and mouse support, the Microsoft executive noted that Xbox One already has keyboard support and that mouse support "[isn't] far away."
@Tak225Th Still finishing Xbox to Win10 streaming right now. I like the idea of Win10->Xbox One streaming but don't have a plan yet.
— Phil Spencer (@XboxP3) July 21, 2015
@lgriao @PNF4LYFE @Tak225Th Yep, keyboard and mouse support for Xbox would need to be there for this to work, those aren't far away.
— Phil Spencer (@XboxP3) July 21, 2015
@lgriao @PNF4LYFE @Tak225Th Mouse is what we'd need to add.
— Phil Spencer (@XboxP3) July 21, 2015