What's this stuff about "incremental upgrade?" Do you have anything to back this up or are you just thinking aloud?
Personally, I am expecting a brand new sensor with superior IQ and ISO performance to the 18mp sensor that is in use. Also, 6 fps, the new digic 5 or 5+ processor, a headphone jack for video, and maybe some other updates for video like high bit rate, low compression codec and maybe better frame rate options.
Also, an updated body with better ergonomics is welcome.