The planet itself has a mysterious connection to The Force that wasn't fully explored in The Last Jedi. As such, it stands to reason that J.J. Abrams might return to Ach-To in Episode IX, as he wraps up the Skywalker Saga forever. While The Jedi have a long history with the planet and its keepers, there's also a darkness deep inside the planet. What's more, A Force Ghost version Yoda even traveled to the planet when Luke was destroying the ancient Jedi text. Clearly there is more narrative threads to pull from regarding Ach-To, and it seems Abrams will do just that with The Rise of Skywalker.