Surely brake fade would not cause the pedal to go to the floor?
Agreed. Brake fade is the term most often associated with overheating and outgassing of the brake friction material leading to a minicule gas layer between friction material and disk or drum. With brake fade, the pedal typically remains "high and hard", but retardation ceases. Not at all the same as fluid boiling.
As trucking-on commented, fluid boiling results in a temporary but dramatic increase in gaseous water in the line with the pedal firmness going to near zero until the fluid cools down. Certainly the braking performance "fades" with fluid boiling, but this is not the common usage of the term fade.
