Cal, think it's the demand. See the below excerpt from the Ford media release that you linked:
"Commercial vehicles: Ford, the only full-line brand with offerings that stretch from Class 1 to Class 7, has a commanding 38 percent share of the U.S. commercial vehicle market. Last year, it sold more CVs than the second, third and fourth place competitors combined."
There is still a LOT of demand for the E series cutaway and stripped chassis units, and there's not really anything that currently replaces them. When you think of the alternate popular platforms in just the RV industry, Mercedes, Transit, Dodge, etc; they can handle the lighter duty demands, but fall short of the heavier requirements. There is very little filling the gap between the light B+ applications and the Super C's besides the 350's and 450's. Add all the ambulance, safety, and commercial applications and Ford has a really BIG market. If they drop the E series, what are they going to use to fill the gap?