This NYT piece has some great data on just how much Chromebooks have destroyed the iPad in the education sector. At a first approximation analysts believe this is simply about price: Apple is the premium vendor and Chromebooks are at the other end, hence making bulk purchases much more palatable for school districts.
But there is something deeper here, a fundamental overshooting of the basic requirements for productive computing that is ripping through the industry in the form of prices that are only going to keep coming down. The laptop form factor is 47 years old, going all the way back to a concept put on paper by Alan Kay at Xerox PARC that described most of the features which the industry would rush to perfect over the next five decades (there is even an excellent book on the development of the Thinkpad, one of the most iconic laptops around that details some of these early feats of awesome engineering before Moore's Law and battery technology was ready to comply.
But buying a premium laptop today is an exercise in burning money along a silly dimension (weight, power, finish) due to how good most screens, keyboards, mobile CPUs and batteries have become (exhibit A is this Macbook Retina I am typing on now— beautiful but utterly unnecessary especially considering the tradeoffs of its svelte form).
Hence the tablet, the industry's attempt to open up the market for a new type of device. However, no real software innovation in the productivity space combined with a long replacement cycle seems to have put out the fire before it could really catch on.
Meanwhile vendors empowered by Google's simplistic OS are likely to keep eating away at the general form factor, something which will be bad for Apple, Microsoft, and anyone else who hoped to hold on to that market.
Finally it bears mentioning that even the impressive growth of the Chromebooks is merely a case of fleas dancing on the butt of the elephant that is the smartphone.