[darryl]

The situation at the moment seems to be that a book with the new typesetting available will:

1. If downloaded directly to an e-ink Kindle Paperwhite 2 or later will be kfx.
2. If downloaded directly to an e-ink Kindle Paperwhite 1 or older will be older formats.
3. If dowloaded for transfer via usb will be older formats.
4. If downloaded to Kindle for PC or Mac will be older formats. Have not tested Windows "app".
5. Not sure about current Android applications including the app on the Fire.

I also don't think there is any real danger of being unable to obtain older formats any time soon. KFX is not currently supported by many e-ink Kindles including the original Paperwhite, still widely used. It is not currently supported by Kindle for PC or Mac. Download via usb is still available for Kindle owners and does not support KFX.

On the other hand, the seeds of a DRM apocalypse are here. Amazon has for the moment the technology to achieve this. As does Adobe. But no longer can those of us using epub simply rush to Amazon with any confidence if and when Adobe's new DRM is activated. I would imagine Amazon has been doing its research on the likely effect of going exclusively kfx on sales of both Kindles and EBooks.

EDIT: Kindle Fire supports new typography. It now appears to belong in category 1 above. Downloading a book with new typography did not appear to place any file in the usual location. I did not actually see where the downloaded file was placed or verify that it was kfx. I did verify that the new typography works.