That is interesting, but it's meaningless as an isolated fact. Yes, it could mean problems for Amazon. It could mean that there has been a breakthrough on price/availability of pixel qi or mirasol or something else, and they are pushing for an early change of platforms. Perhaps they have seen the new Google Nexus Tablet and they are thinking of concentrating on apps instead of hardware? Perhaps estimates were just too high? There is always a number that is too high (you make more than you sell) no matter what your estimate is.
Another thought: As Kindle's move from book fanatics to mass market, I expect their sales pattern to change. This means a huge sales surge for Christmas and slower for every other season. As a result, they only need a trickle of current models and they need to begin working on whatever model they will sell next Christmas.