There already is crossbows breaking the 400FPS speed barrier...however as nekred stated..its still a crossbow...many think they are like a rifle for accuracy and distance...crossbows are still only as accurate as the nut behind the string and basically same distance as a bow...
There are bows out there plenty fast at 360 FPS and they are bows and as accurate as any crossbow...
Not sure what your point is?
JMHO
Neil