Default [Q] 4G/LTE bands permanent?

Hello all,

I am thinking about picking up a Galaxy tab S 8.4 (T705), to use as a new phone. I noticed that is doesnt support the LTE bands for US AT&T. While doing my research, I found it mentioned that the T705 was coming to AT&T sometime.

Seem to remember back in the old days (Geez, I sound like an old timer), on the old HTC TYTN's, that we used to be able to flash a radio, to pick up different bands. Its possible I am incorrect, it has been some years.

Was curious, does anyone know if I picked up a T705 with unsupported bands, would I be able to flash the device to get the correct ones at a later date? I suppose I would have to hope someone did release it, but just wasnt sure if the bands were permanent with these new devices, or not.