Leafing through a PDF (legal) copy of Dark Heresy and comparing it to Black Crusade I came up with lots of differences, the main one being BC is easier to understand!
Considering DH is FF's best selling, and best supported 40K RPG, is there room and a requirement for the entire rulebook to be rewritten and updated, without changing the core rules (much, so supplements are all still fully functional).
I think there is, and quite a big need at that, how about you?