TouchID is not returning.They won’t do away with the X or at least it’s features. Apple might bring back Touch ID if they can get it under the screen but won’t go back to an all design when the rest of the industry are doing bezeless designs.
I've posted a link here in the past where an Apple official has stated that under the glass TouchID was never a consideration. Apple's focus was on FaceID and that is what they will use going forward.
So, any hope that TouchID will return because there is a problem for Apple to solve first is false hope - because Apple isn't interested in Touch ID any more. Period.