At first glance the sideline rule looks like it is going to be a pain to deal with. Most coaches are already coaching from the field and then backing up 2 yards(or more) to get back into the coaches box.
I would hope all officials will work with the coaches and vice/versa to allow/remind them to get back as soon as the play starts. My feeling is that most officials do not want to make this call and will work with the coaches.