10. The Return Of Anakin Skywalker
After months of anticipation and speculation, Prequel fans were disappointed that Anakin Skywalker did not appear in The Rise of Skywalker. Episode IX's name, and the fact that Anakin/Darth Vader formed the backbone of the first two Trilogies, seemed to assure Hayden Christensen's imminent return, and Prequel fans were understandably let down by Christensen's short and jarring voice cameo, believing that the character (and actor) deserved more respect.
Given that Obi-Wan entered into exile in Tatooine after his best friend and apprentice fell to the Dark Side, Anakin's potential to return is pretty obvious here. The series could flashback to dark Anakin moments we never saw on film, as his old Master tries to understand just how he could turn, with Kenobi processing some of Skywalker's less-than-Jedi-like behaviour in new ways.
But there's a chance that the Obi-Wan series could give us more than just flashbacks. Due to Vader's ambiguous "a presence I've not felt since..." statement in A New Hope, there's always a chance Obi-Wan and Anakin/Vader could have an entirely new encounter, giving fans a chance to see Darth Vader at the height of his powers.
If this is the direction Disney chooses to head down, they should still give Christensen a role, perhaps revealing a glimpse of his face behind the mask.