ABC has issued a statement and you can see it on Soaps In Depth . After the fans kept campaigning for her to stay, the bosses wisely decided to keep her on. How this will effect storylines/scoops I'm not sure yet.
The statement issued says in part, “Rebecca Herbst will continue on as Elizabeth Webber. The show is thrilled she will remain on the canvas to portray the beloved character in many more poignant and emotional stories. Fans will be pleased to see Rebecca continue the role she created.”
On a side note, ABC may be trying to backtrack on this whole thing, blaming the "reporting" of her leaving GH as being "overstated"--what a bunch of sheeze-wacky. They fired her, they saw it was a stupid move and canceled it. To say anything else is pretty laughable at this point.