A while ago, Phil Spencer commented on the possibility of original Xbox backward compatibility on Xbox One, mentioning that the team had to finish Xbox 360 emulation first.

Today, Xbox and Windows Platform Director of Program Management Mike Ybarra gave more color on that during a a podcast hosted by The Inner Circle, mentioning that it would be very challenging, but also that the team would love that challenge.

"We're not looking at original Xbox games on Xbox One yet, and right now the focus is making more 360 games work, but I would say that nothing is impossible.

Certainly, it would be very challenging. Gettibng 360 to work was incredibly challenging, and really a multi-year engineering investment going all the way back to the original [Xbox] certainly would challenge the team. We're fortunate enough to have a great back compat engineering team, who loves to take on challenges, and I'm sure they would love that one as an opportunity to go look at."

There were definitely many great games on the original Xbox, and I would certainly love to play them on the Xbox One. Hopefully the Xbox team will be able to tackle that challenge one day.