I think quality has a long way to go yet. We might get some minor price decreases, but mostly new releases will be feature adding.
In about 2-3 years the technologies will be sufficiently advanced that most new releases will be adding minor features, but getting cheaper. Eventually It will be similar to the iPhone which now just adds somewhat minor features (like 3G) and lowers the price.
But until all of these readers have color touchscreens, internet access, easy to read display technology like mirasol but better, and better form factors and high battery life, they have a lot of technological improvements to achieve.