Alas, no, the nipples stay the same size unless you have them surgically reduced. As for overall breast size, it varies a lot from person to person. Some people have a lot of solid breast tissue in there, and don't change much in size. Others change dramatically. I know one guy who started as a large B pre-T and ended up small enough that he became a candidate for peri-areolar surgery. Most seem to go down about a cup size.