Yeah, the hard part would be the Matrix, which was it's own minigame back in the earlier editions (And every other Cyberpunk game ever made.). 4th has done better than another other system I've seen yet.
Not saying it still doesn't need work, but then again, everything can be improved on. Such is evolution.
The issue would be converting the old adventures, I think. The fluff doesn't change, but the stats certainly do.