The bottom speakers part is cut out anyway, so it shouldn't be a problem.
And the thing that makes me think that the XS cases do not fit the X is because Apple would've mentioned it on the site, because they've stated that both iPhone 7 and 8 cases are compatible. But it could be because the X is now discontinued. Just wait till Friday, no big deal.
[doublepost=1537114713][/doublepost]Edit: Comparing images of iPhone X and XS case, the camera is slightly lowered and more to the right, it could have gotten bigger.