Can they, yes. Just about anyone can be used for just about anything.
Should they, no. Why should Amazon continuously support, checks notes... 14 year old devices??? Likely the number of customers using a device like that anymore is super small.
The network service side of the product should continue to work because the company sold that.
Unless you can find where the original advertisements (not microscopic fine print) said that the company would disable the network service side after a period of time, such that the buyers knew that's what they were buying, then the company is obligated to continue operating the service they sold. Or negotiate some alternative satisfactory to the buyer.
how well does the battery hold up after that long?
Mine is only like 2-3 years old and I charge it so rarely. I can read several entire books on a charge easily. It lasts months. I imagine even if the battery degraded significantly it would be quite usable.
I replaced the battery in mine. Unlike big tech, I believe in repairing old devices.
Something Amazon have not considered is how many of these old devices are used as companion devices for other high end kindle owners. I have a scribe and old paperwhite and use them interchangably, with cloud sync of reading position etc, which won't be possible after 20 may.
My paper white is about 7/8 years old, and is still holding up fine though the battery is noticeably degraded - charging it approximately once a week now.
I was also having a play with a demo model of the latest one in a store and the page turn speed is much much better, which is tempting me to upgrade though I'd prefer to run the current one into the ground first.
And a lot more people use github for something at all and don't use Apple for anything at all.
The entire Apple universe is smaller than the world or even just the github part of the world, and the Apple developer universe is a tiny fraction of even just the Apple universe.
Should they, no. Why should Amazon continuously support, checks notes... 14 year old devices??? Likely the number of customers using a device like that anymore is super small.