Sales have dropped because:
1.
a) The hype has somewhat passed. Most people that bought a Netbook in 2008 have little reason to buy another one as Intel hasn't given them any reason to do so. Current Atom are still being built with 45nm technology, while Intel has been selling CPUs built on 32nm technology since the beginning of 2010. Intel has just been milking the 45nm node. And now all of a sudden are going to release 32nm Atoms later this year, and within a year, 22nm Atoms. So, 3 years at 45nm, and now just a year at 32nm. Wonder why it isn't selling more 45nm Atoms ?
b) The Dual Core Atoms N550 and N570 are actually good performers, capable of decoding 720p in software, both offline and online (720p flash videos), but they get hot for such small platforms, with an 8.5w TDP. And then the GPU hasn't changed and you can't even play with acceptable framerates or even correctly render Half-Life 2, which came out in 2004, and the platform is still using 1.5v DDR3 that can also get hot because it is not actively cooled. The 32nm Atoms must use 1.35 or better yet, 1.25 low voltage DDR3 so-dimms, to improve battery life and perhaps more importantly, reduce heat output.
2. AMD has come to market with better offers. Their C-30 is good competition for the N455; their C-50 is good competition for the N550, and their C-60 is even better than the N570. And I'm only talking about CPU performance. AMD wins in GPU performance all days of the week, plus it already supports 4GB of RAM, and the platform also supports HDMI out, something Intel has yet to provide. We'll have to wait for their 32nm Atoms for that. Meanwhile AMD has already sold 12 million APU's, including the Netbook oriented C-30, C-50 and C-60.