The first excess bid will flush guys down to the narrowbody FO seats, but not down to the 727/SO seat (...because those being excessed are senior to the most junior guy in the 727/FO and 757/FO seat).
We won't know how many guys are flushed down to the 727/SO until we see the size and scope of the subsequent, and more junior, excess bid(s).
(...and remember, the 757 needs to grow!)