I find it utterly improbable and unacceptable that the crew didn't make it! I still believe that finding the reason for this will be a major contribution in establishing the cause for the disaster!
Other flights where no mayday was made before they perished:
Perpignan A320
UA585 Colorado Springs
Continental Connection Flight 3407, Buffalo NY
EgyptAir Flight 990
AirFlorida flight 90, 1982
Copa Airlines Flight 201, 1992
They all had time to key the mike. No value, unaffordable, counterproductive. Perhaps if you ever have an urgent crisis you'll understand. Perhaps not.
Amoung those who did: (radio calls)
USAir 427, 1994, ("Oh [unintelligible] Oh [expletive]" and "427 emergency")
Alaska Air Flight 261, 2000, ("Mayday")
I ignored flights where they crashed just short of the runway in bad weather, and a number of others which crashed just after takeoff. It wouldn't be fair to you to add these.