And finally, I would like to reveal some of the links to incidents, which have lead me to asking my scenario question... just so you guys know where I was coming from:

This one showed me that brakes can fail and elevator can fall "upwards"
http://www.youtube.com/watch?v=ijLywn1-2Gg

This one showed me that the fail-safe brakes, which should stop elevators from plunging may not always work:
http://abclocal.go.com/wls/story?id=8601546

And this one showed me, that an elevator car can hit the ceiling with hard enough force to kill:
http://www.nytimes.com/2004/08/13/nyregi...s-sq-tower.html

All of these incidents played a part in my initial question above.