Do flight attendants have a regulatory responsibility to risk their own lives to save passengers?
In training, flight attendants are given lots of emergency training, but always with the caveat that they are under no obligation to put themselves in danger.  Emergency procedures should proceed up until the time a flight attendant feels they are in danger, then they are to evacuate the airplane themselves as quickly as possible.  

There was a long standing joke among flight attendants when I was working, which was the most important emergency instruction you can give:  Follow me!  Funny, but not really.  It keeps things in perspective.  Not commonly known is that any emergency responder today operates under the same conditions.  You are not being paid to put yourself in danger beyond what your training will accommodate.