What Will Happen When Teachers Just Say "No" in a "Tenureless" World?

Where did this apple come from?

What will happen if teachers just say "no" and there is no tenure?  You probably already know.  You will be dependent upon the good will of your supervisors.  Suppose a teacher is needed to "volunteer" to teach a sixth class?  It pays money (which may take some time to roll in), but it may not be convenient.  You may have family commitments which outweigh your need for more money.  Don't tell me you can just say "no" and there won't be "payback" by some administrators in some schools.  And, even if there is not "payback" in some schools, teachers will most likely act on the premise that it is a real possibility.  

As it stands now, new teachers are usually the first ones asked to perform the less than desirable tasks.  Perhaps, it is felt that older teachers have already put in their time as gophers.  Perhaps, they don't run as fast anymore.  Perhaps they are no longer dependent upon the good will of administrators to receive their tenure.  They've worked their way up; they've earned a little more status.  Without tenure, career teachers have earned nothing.  They may be constantly "under the gun," under the beck and call of supervisors.

Suppose a teacher blows the whistle on violations of federal law governing services provided to students, administrative abuse of funds or something else.  Without tenure, teachers will have far fewer protections.  I'm guessing rather than suffer through a long process of seeking redress, most teachers will look the other way and shut up.  Who suffers then?