First, you talk to the guy that hit his brakes too hard and tell him, in no uncertain terms, not to do that again.

Second, make sure that you have room to move either to the right or to the left. You shouldn't be overlapping wheels with the person in front and the person behind shouldn't be overlapping wheels with you. So the bailout to the side shouldn't take anyone down.

Third, always focus several riders ahead of you, so you have more time to react. Of course, if the person braking is right in front of you in mid-pack and hits the brake for no apparent reason that may not always help.