rare possibility...
It seems to be an extremely remote possibility that on line you would ever lose both generators at the same time on takeoff roll. What you could lose is , both engines on takeoff roll, that would also mean losing both gens..
Before V1, every master warning activation calls for a rejection. It requires a bit display of automatic behaviour from the pilot.
listening CRC while hand on thrust lever = REJECT.
to stop the airplane, use full reversers, full brakes. In new A320s you do not have to worry about 1000psi limit, system takes care of it. so just stand on the brakes..
cheers