I am going to suggest Organic Electro-Luminescent Display:
https://en.wikipedia.org/wiki/Electroluminescent_display
It's not quite a Samsung-style AMOLED smartphone screen but it comes darn close! This was DEFINITELY chosen for battery consumption reasons so it doesn't drain the battery so fast. It also means the EFV display frame rate is at or faster than 60 fps which is PERFECTLY FINE for a small mirrorless camer. This means lag will be AT THE MOST 2 or 3 video frames or somewhere between 40 to 120 milliseconds (or around one-tenth of a second) which is ALSO JUST FINE for working as an optical viewfinder replacement!
It looks like this will be a decent camera from Canon --- I can't see too many issues with it so far. BUT IT BETTER HAVE 10-bit 4:2:2 Interframe 4K at user-selectable 75, 150, 200 and 300 megabits per second in order to make it competitive with the Panasonic G5-series or the Sony A7S2 series.