Let's just wait and see which of our numerous suggestions Jussi tried to build in. I just hope that it's really gonna be an improvement. DSJ3 compared to DSJ2 was basically the same game except for better graphics and online play. On the downside, the rewind feature was not as good as in DSJ2 and single player world cups with 50+ CPU jumpers (to make it "real") didn't really work because you could easily read a book in between your own jumps. And this is basically the one thing, directly compared to DSJ3, that is really important to me: Fast calculation of CPU jumps so that single player can be played again.
Apart from that, the two things I'm hoping for the most are different gates (instead of speed-manipulation by wind in the in-run, which is simply unrealistic and therefore not really worthy of the most realistic ski jumping game in the world) and a career mode
Something I was also thinking about as of lately: A sort of "record hunting mode" with the wind still being random, but random between 1 and 4 m/s headwind (and the headwind also still from a random direction, but still mostly from the front).