I don't mind EVF, but here is what would be nice improvements:
-The K-5ii now has a better screen, put that on the K-01
-add tilting and swiveling to the K-01 screen
-EVF maybe, a lot of people claim to want it, I don't care much. If they add it, it should be unobtrusive and should not try to look like a DSLR VF, but rather should be incorporated into the overall K-01 style
-Improved button placement (especially red and green buttons)
-More video output modes (some videographers want 4k video and stuff)
-Peaking during recording video
-and keep the overall design, with only a few changes where needed (for example the SD card door, a lot of people are whining about it, even though I had no problem with it so far)
-Add an all-black version for people who are afraid of colors and have a pathological need to "look pro"
Beyond that, just standard improvements in AF, sensor technology, noise reduction, better camera cooling, more detailed screen, uncrippled mount, if they go for that etc. Of the K-01 I like the solid build and the image IQ, the long battery life and its compactness.