Xbox one isn't doing nearly as well as PlayStation in Canada (Part of North America) and U.K. which makes up a huge chunk as well. The other countries do help, but not nearly as much.
The biggest problem MS will have at the start of next gen is PS5 most likely having backwards compatibility. Unless Sony don’t screw this up, I doubt MS will have a chance of getting close worldwide. They might have a chance to lead in their home market, but it’ll be nowhere close to how it was in 360 times.