Ok, so here is a Samsung Galaxy S8 back panel. We can clearly see the hole for the fingerprint sensor to the right of the camera. At first I thought that looks like an awkward placement for a fingerprint sensor, but after imagining and trying the placement on my Nexus 6p, I think it could be quite good. And if the rumors are true about the new really fast facial recognition technology it will use, you won't use it much anyway. I can guess that the only time you will use the fingerprint sensor on the back is when you are in a dark room so that the facial recognition doesn't work. By the way, the color of this Samsung Galaxy S8 back panel looks quite nice.
Via Slashleaks
Via Slashleaks