Good e-Reader reports that Amazon will stop wireless Send to Kindle on devices it has moved to unsupported status - meaning older hardware loses the frictionless email-and-cloud pipeline readers relied on for years.
The practical fallback is sideloading over USB or buying newer hardware if you want first-party sync. For anyone clutching a decade-old Paperwhite, it's another reminder that e-readers age out quietly until a feature disappears overnight.
(Shortened and summarised to avoid devaluing the source)