Board Thread:General Discussion/@comment-25613119-20150306103812/@comment-4839682-20150306105638

Not sure where you're getting "join the main cast", as your article doesn't mention that, but:

"Executive producer Adam Horowitz mentioned that her initial appearance will be brief, but there is the chance that more of her will be seen later in the season. There are also speculations that she would join the show for the following seasons."

"chance", "speculations". The creators always leave the door open to the possibility that characters will return.