Actually it appears they are proposing to allow the back foot toe to be behind the rubber as much as desired making things easier for the pitcher.
"While the pitcher takes the signal, her stride foot may be on or behind the pitcher’s plate as far back as desired. Once the pitcher initially sets the toe of her stride foot, she cannot move it to increase the distance behind the pitcher’s plate. In addition, the pitcher must take or appear to take a signal while in the pitching and signal-taking positions."
That would be more like high school rules, right?