Xbox One Backwards Compatibility - Nothing is impossible.

Microsoft has again reacted to the suggestion of making original Xbox games playable on Xbox One through backwards compatibility.
Xbox engineering boss Mike Ybarra raised the subject on The Inner Circle podcast, saying the feature hasn't been ruled out, but you shouldn't expect it to come anytime soon. "Nothing's impossible," Ybarra said, adding that Microsoft's current focus is adding more Xbox 360 games to the backwards compatibility program. Xbox One backwards compatibility works by emulating the Xbox 360 operating system. Getting an original Xbox emulator up and running would be a tall, but not impossible, task, Ybarra explained.

"We're not looking at original Xbox games on Xbox One yet," he said. "Right now the focus is making more Xbox 360 games work. [It would be] certainly very challenging. Getting Xbox 360 games to work was incredibly challenging and really a multi-year engineering investment. Going all the way back to the original certainly would challenge the team."

There is still a chance, however."I'm sure they would love that one as an opportunity to go look at," he said.