The term "nosedive" is typically used to mean disastrous: literally diving only to land on your nose. Did you mean "head first dive" (which means "going for it, all in" as opposed to "dipping a toe") or are you projecting that Apple is plummeting into a crash and burn situation by getting into watches?

Also, Pebble's "massive success" with whom? The only people who know about it seem to be those who hang about on tech blogs and forums and crowd sourcing sites. It hasn't crossed the chasm.

Apple's key strength has always been, from Apple II to iPhone, crossing the chasm to put a tech category into the hands of normals.