3G and 4G Bands for all Countries. (At least One band usable for all places ppl visit)

Low power display, I.E. OLED
Keep TOH (Useful for keyboards, increasing battery size etc.)
More open SOC, Preferably something the Modem can not read memory/filestorage. (Something that I can reflash all binary objects to factory including modem firmware. In the event of visiting locations suspected of hacking the modem.)
Kernel able to boot multiple volume BTRFS file system, so SDCARD can be used with root pool. I.E. add 64Gb to internal storage. Card would need to be reliable and fast, as it's removal/failure would break device OS.
NFC available for general use other that TOH

Improve Specs mainly for future proofing device. (Hey not easy to get this device every 2 years)
# CPU cores, ram and camera.

Ability to purchase from around the Globe (Australia pretty please)

The rest is the OS which is improving at the moment anyway.