It has been reported that amazon CS said that the new touch firmware will have landscape support and a "new interface": https://www.mobileread.com/forums/sho...d.php?t=174904
Of course, you can always use MfgTool and fastboot to downgrade a new kindle to a previous "open" firmware version.
I am anxious to get a copy of the new firmware from one of the new multi-language kindles to compare against the current 5.0.4 firmware. This sounds like a MAJOR firmware update.
We might even need to use a new jailbreak method to add hacks to the new firmware. This could be interesting...