damirc:
"ust to clarify. The RAT would (as far as electrics go) only power the AC ESS and DC ESS buses, so the ACARS subsystem would remain unpowered."
I appreciate that a RAT wouldn't power ACARS - but it would provide hydraulic and electrical power to continue control of flight control surfaces.
To date; we don't have evidence of dual-flameout, but we do have evidence that the sensor system delivering airspeed, altitude and AoA data to the pilot suffered from icing and was unreliable.
Data so far points to it being it more likely that the aircraft was stalled into the water under power, rather than a scenario where both engines flame out almost simultaneously (without fuel starvation) and auto re-light also failed. We know it wasn't a planned ditching attempt, since lifejackets were found in their containers and flaps were retracted.