The eBook Reader emphasizes that even when Amazon dials back cloud delivery, older Kindles still accept sideloaded books over USB - Calibre, drag-and-drop, and old-fashioned file management keep the hardware usable.
You lose the seamless Whispernet fantasy, but you keep reading offline without buying a new slab. For travelers and DRM-aware readers, that trade has always been acceptable; for casual users, it's the moment they notice the ecosystem tax.
(Shortened and summarised to avoid devaluing the source)