Yep, Nikon is in no danger, thats for sure.
But for a company that invested heavily in FF models, the assumed future course of DSLR sales, and then misses its forecasted sales naturally raises the question "What happened - is FF the future or not?" The irony is not to be missed. Nikon succeeded in their planned FF expansion and their stock went down.
The reason Nikon gives may actually be true, or there may be another reason that Nikon doesn't competively want to identify. I assume there will be a lot of headscratching going on in the industry as to the actual story for at least a few more days