There is no answer that will be correct for everyone - your standards of sharpness are unique for you. Since the D100 is basically known only by its specs, any comments on it are subject to what kind of image quality it demonstrates when it becomes available.
By resolution alone, the 3008 x 2000 resolution should easily produce sharp prints up to "8x10" print size. I would bet that you could get quite good quality up to 11x14. To get to 20x30 inches, you would need to resample the image file and the results won't hold up to close inspection. But then not many 35mm film images could hold up to such enlargment and be considered "sharp" by many people. I personally would use a medium format film camera if I regularly planned to make 20x30 enlargements.