I actually think K3 could be released in the next couple of months. Amazon has been releasing a new piece of hardware about every 4 months or so:
K1 - 2007 November
K2 - 2009 Feb
DX - 2009 June
K2i - 2009 October
DXi - 2010 January
Here we are in April, 4 months since DXi. So by this line of idle speculation, K3 could come any time. It has already been a longer wait than between K1 and K2 releases. I would expect the next K2/K2i update (improved accessibility, 'organizing') around the same time, just because I want something new also (not planning to get a K3 myself). <g>
There's plenty they could do to improve on K2, short of adding color:
- make it faster
- internationalize the hardware/software (for non-English languages). This would probably mean scrapping the so-called keyboard and replacing it with a touchscreen (either a second screen like Nook or a single touch sensitive screen for reading and typing). Kindle is really the only dedicated reader device that is so strongly tied to the English language, and Amazon needs to address this if they want to compete globally.
- improve screen contrast
- lower the price to $300
I think there's also room for a slightly smaller, stripped down, sub $200 reader without a keyboard or touchscreen. You'd still be able to enter text (using joystick) but it would be slower.