If you have seen the doco produced about the development of the 777 (5 hours, was shown as a series a number of years ago) the original engineering philosophy was to DESIGN an aircraft which did not require pilot input. This design was then downgraded for the production aircraft because of certification restrictions and perceived passenger resistance. The flight control system is not capable of auto takeoffs, but how much modification would be required only the engineers would know. 200 ft min for the autopilot is only a cert restriction. I know in the sim, the autopilot does a wondeful job after you have set the attitude on rotate, makes no difference 1 or 2 engines.
while not cert to, it handles the yaw just fine, TAC on or off.
I would think that AB, being more inclined to push the boundries of auto flight, will be the first.