In the past Samsung's phones had fingerprint scanner situated in the "Home" button. Later, in Galaxy S8 firm decided to reorganize visual look of phone and fingerprint reader was moved to back, to place near of the camera which causes that people often misled reader with camera and they dirtied camera's sensor.
How it turns out, probably in Galaxy Note 8 situation won't change and fingerprint scanner will be situated on back. Although Samsung already confirmed that firm is working on solution of this problem, and company tries to make fingerprint scanner which will be situated under the display. How say analysts, this option won't be ready for the moment of Samsung Galaxy S9's premiere, and fingerprint scanner will be firstly located under the display in Samsung Galaxy Note 9. It's not a secret that another company which tries to make this fingerprint scanner is Apple, and we must wait to see which firm will solve the problem faster.