Yeah, I think "brace yourself" is the best advice. According to LSN, Duke hasn't rejected anyone yet. So I'd say that a truckload are due.
What are your numbers and index? I have a 3.4 index. 3.6's have been admitted in droves and 3.5's heavily as well, but then there's a big drop off where few 3.4's are admitted. And judging from the number of each index on the LSN board (which I'm judging to be fairly representative of at least the top candidates) there are a LOT of 3.4's so I don't think they'll ever get to the 3.3's much. They will probably see who ends up matriculating from the 3.5+ folks and then fill in some with the 3.4's and lower only at the very end.
Of course I could be smoking something. They seem to be admitting way over their medians right now. 3.73/170 is definitely not their median. So in fact forget all that I just said, they've GOT to admit some lower people unless the quality of their applicant pool has really really ramped up this year.