User blog comment:Kaijusaurus-Rex/Season Six Info and Leaks!/@comment-33454827-20180426152645/@comment-34469350-20180609092601

It's been four seasons since her first and only appearance (if you don't could that flashback from "The Matchmaker"), if she was planned to reappear, it would've probably already happened. There's only 19 episodes left of seasons 6 that we do not know anything about (20 if you count "The Future"), meaning that the season's probably going to have to start to dig into its final grand story quite soon, leaving less and less room for episodes focusing on minor characters, such as Rachel.