Isn't the headliner black when you get white seats? As well as having dark wood and the dark floor.
So, not all white by a long shot.
Interestingly, if you order the new cream colored seats, the accompanying headliner is white. So that might be more overwhelming than white on white
I plan on ordering the model 3 in white interior so I'm not exactly sure what that will look like but it does seem like the X and S have good contrasting black/dark colors with the white interior