I don't think that more megapixels will help, whether it's physical subject distance, FPS, cropping for composition or whatever.
The best sports photography - sharp action shots, frozen in time at just the right moment - I think are best served by the D4. Lousy seats and not enough focal length? Move closer. Serious about sports shooting? Develop a relationship with convenors and venue managers in order to gain access to the preferred shooting positions. The best shots, generally, are made from court, field, floor and ice level. I think sports shooters need the D4 speed, superior high ISO results, fast glass and the best, stable shooting positions low down. It is inherent sharpness that determines how heavily an image can be cropped, not megapixels. Blurry megapixels are blurry megapixels. So all you get out of a heavy crop of a loosely composed, blurry/soft, original shot is a tighter, blurry/soft shot. By comparison, a loosely composed sharp shot, is more likely to soften slightly after being cropped tighter. The former is useless; the latter is quite often perfectly good. It's one of the reasons that sports shooters have gotten razor sharp action shots using 4, 6, 8, 10 and 12 megapixel pro cameras. The 16mp in the D4 are even more astonishing by comparison. Get closer, shoot tighter, crop less. The 16 gorgeous megapixels in the D4 are not exactly chopped liver. It's one of the best sports shooters (or any other kind of shooters) ever made.
The key to sharp shots is less distance between you and the subject, not additional focal length or cropping. The farther away you are from an action subject (or any other subject), the more that distance relationships appear to be compressed - a characteristic of telephoto photography. That can be a benefit or a curse, depending on the subject and its environment and the background against which the shot is captured.
I crop. Everybody crops from time to time. Sometimes it's unavoidable. But I think that enormous numbers of megapixels have hurt technique. We should all work smarter to eliminate cropping from our post-processing.
If we're 'voting' I say go for the D4 for its speed, high ISO superiority and top-notch technical image quality. Then get closer and shoot tighter.