
Apple killed the competition then deliberately dumped the market...
iPod sales are down because they keep junking the decent ones...
People were going mad for the 6th generation iPod and the Lunatik strap - Apple's response - double the physical size of the device, kill the market and take 5 years to come out with their own 'watch' that doesn't even feature-match the iPod-strap combination.
Then there's the Classic - it makes for a great car jukebox when used with an audio system that plays nicely with it. Better than the alternative of a big USB stick.
Apple pushed the iPod Touch - great for the sausage-fingered masses who only want a device if they can poke the UI but a major step backwards in capacity.
Apple killed the iPod market themselves. Nobody else to blame.