Losing the head rooster will change a flocks dynamics, and chickens don't like change. They should sort it out eventually.
Or it may be that the timing of the alpha rooster's culling coincided with something else that is causing the hens to stop laying. Lice and mites have been mentioned. But it could be something else, too. Even something as small as a change in feed or something new being placed in the coop can set them off. So a little investigation on your part might find a different cause for the problem.
As for aggressive roosters, you did the right thing and I think you should cull the current one, too, since he attacks people. If the young replacement you have in mind is related to the other two then it might be time to start fresh and bring in an unrelated rooster. Aggression in roosters can be hereditary.