Same case with Sidney Fullmer, who was discovered at an American Girl store and eventually landed the main role in the Saige movie.
Vaporware: Rumors of a new American Girl doll, Rebecca, began to surface in the adult collector community as far back as 1998, when Mattel trademarked the name of the character. Eventually details leaked that she'd be the first Jewish historical, and after that, she seemed abandoned, with dolls such as Native American Kaya and '70s girl Julie (and the entire Best Friends line) appearing instead. Rumors of prototypes of Rebecca being seen by company insiders floated the entire time, with various descriptions given of her appearance, but most of the collecting world had given her up as an idea dumped on the drawing room floor. Following the retirement of Samantha in 2008, American Girl finally confirmed they were producing Rebecca, who was released in May of '09.
According to this article, Rebecca was planned to be released in 2004, but then was pushed aside as the company focused on the American Girl movies.