At E3, it was announced that original Xbox games will now be Xbox One backwards compatible. Sadly though, it looks like some of the games will not have widescreen support.
Phil Spencer replied about the topic on Twitter. He said: “No, most OG Xbox games didn’t have WS. Can’t really easily change the frame buffer aspect ratio on a shipped game from BC.”.
It appears most of the games will stay in their normal aspect ratio. They don’t want to stretch the image to 16:9 or else the image quality will dip.
We will just have to wait and see once the first Xbox games get converted. Original Xbox game support is supposed to be rolling out sometime later this year. The first game confirmed is Crimson Skies.