Hi ,
It makes me think that you lose just the ability to maintain a straight track ... but not the ability to roll the aircraft.
Correct.
In order to maintain a constant heading at VMCA, you'll need bank into the live engines.
The danger is if you attempt to fly wings level with the ball centered, you may run out of aileron control.
This problem will only occur at very light weights, when V2min = VMCA (or during the GA from an approach when VAPP = VMCL (VMCA in Landing Configuration))