another possibilty is a worn master cylinder bore......they are alloy and can get scored/worn due to age(mileage)
a friend had his brakes COMPLETELY fail with no warning on a 4 yr old acura i was with him and can vouch for the ZERO braking ability
thankfully we were going slow (30 mp/h approx) and the e-brake worked well
but yes........it was the master cylinder worn out........
i have had civics do the same thing but with warning IE: mushy pedal.....
just a thought.........