According to a post by an anonymous user named “Foxconninsider” that surfaced Wednesday morning on Reddit, Apple is allegedly working with a startup called Sonder on a next-generation Magic Keyboard that's supposedly outfitted with an individual e-ink display on every single key.
Having e-ink-enhanced keys would let the graphics on each individual key change depending on the app currently in use. To me, that sounds a lot like an OLED strip that the rumor-mill believes will be debuting on the next MacBook Pro.