So, what are these 'under-glass' finger scanners that may be on the Galaxy S8 and iPhone 8?

TL;DR

The "under-glass" finger scanning solutions already announced aren't really "in-screen authentication," but they may still lead to the rumored nearly edge-to-edge displays of the Galaxy S8 and OLED iPhone 8.

Home key begone!

By now every geek worth their mettle, and everybody remotely interested in the grand rivalry between Apple and Samsung may have heard that their 2017 flagships - the Galaxy S8 and the iPhone 8 - may ditch the home key. This would bring them one step firther to their rumored "edge-to-edge" design, as they may get thinner, uninterrupted bezels. 

Especially ...