That's the thing about a wing back, they always look right-now and fit into traditional and contemporary style if you pick a great fabric like this!
I really like the idea of wallpaper for a stairwell, especially one that is cramped or you can't do much with because of its height or other constraints. However, I would pick a much more fabulous wallpaper than this one. It would absolutely need to be something you can live with for a while. And the chandelier in this photo, sorry but, "heck no!" Doesn't look by the railing that it is in an ultra modern home so it just doesn't go.
Still the wallpaper is a great idea. I would add some roman shades that complement the wallpaper and cozy up the space even more. Or maybe some frosted graphic birds. A great wallpaper with some painted stairs are even better. I really like this "new" trend as it is a great way to personalize the builder-box house. I grew up in a home that had painted red steps leading to the top floor. Don't know what that was all about, but what's old is new: