Even if the developers take the egregious step of nerfing airplane mode, you can still "opt out" by not giving the device credentials for your WiFi network.
Yup, this was once a thing - you didn't need wifi for sync or downloading books at all.
eta: My point being: Now you're in a twisty little maze full of corner cases, all different. Not the sort of thing much loved by Amazon (or any of the GRAFT).
> if the developers take the egregious step of nerfing airplane mode,
and I was responding that IF the developers decide to nerf the airplane mode it's very possible they will start using any open AP; some TV's are reportedly doing this already
Literally any device you own with WiFi could be updated tomorrow to connect to any open access point.
It doesn't seem so far-fetched that the Kindle might, too.