[felisml]

I'm not surprised at all...the whole point for Amazon is ebook sales, they want install base, it's nice if you upgrade your device but many people will keep paying for books regardless of device version.

Throwing a few engineering headcount at keeping updates going as needed is more than worth it, and a more exact "when do we stop supporting this" trade-off can easily be calculated against usage and purchasing data since they have vertical integration to that degree.