Swivel screen would be a huge plus for me. So often I find that a photo will appear much more dynamic and interesting if composed from above my head or at an angle that is awkward to manage or
from very near the ground, and with a fixed screen this is next to impossible. Other small improvements to current k-5 features would be great to, such as the ability to shoot bracketed photos with the intervalometer for HDR time lapse. Of course a video mode revamp with dedicated button, continuous AF, 24p options, higher framerate options, adjustment of aperture and shutter speed during shooting, etc. goes without saying.