I really doubt that we'll see any kind of brand new screen tech for the EVO. There are very few companies with the R&D and the factories to make displays, and HTC and definitely Sprint are not among them. HTC buys screens from other manufacturers (I believe Samsung makes the AMOLED panels for the Nexus One/Desire/Incredible). Also, since we now know that HTC is going with Atmel to provide the touchscreen tech for the display, the screen will definitely not be Super AMOLED, which has the touchscreen built right into the display.
I'm a bit ambivalent about the screen choices. I'd love the vibrance and black levels of something like AMOLED, but would also love the sharper screen and daytime visibility of a traditional TFT LCD. So in the end, it might just be a wash.
I do hope that Sprint gets the phone out SOON though... I've had an upgrade available since December, and it's been 5 months now waiting for a viable high-end phone. It seems as if we have 2 months left to go... but I'm itching to get something... and might just go with the Verizon Incredible because of my lack of patience... Forgive me...