Great question, I remember someone asking this about the "evo 2" in a thread a year ago, not sure which website though(either ppcgeeks, androidcentral, androidforums or xda) and my wish list actually turned out to be the galaxy nexus. Before much was known about the gnex or ics I wanted the "evo 2" have a larger screen than 4.3", I wanted a phone with no physical buttons like honeycomb, I also wanted a 720p screen with a dual core processor. I wish I could find where I posted that.
Anyway as far as the "evo 3" goes, I am hoping for pretty much the same. It better have a 720p screen, at least 4.7" screen, super amoled plus(year right), good camera with zero shutter lag, 32gb of storage, razr maxx type battery. As far as processors go, I was very excited with the thought of having a dual core processor in a phone but I honestly believe that quad cores are overkill so the evo 3 having a dual core or a quad core isn't that significant to me.