This episode was pretty good but it seems like it's too early for it, if Maul vs Ovi-Wan is being hyped for the finale then we still have quite a ways to go first.
Anyways I guess it makes sense Obi-Wan is the key to defeating the Sith, otherwise Luke wouldn't have left Tatooine or would have known to go to Dagobah and see Yoda. I was thinking Luke was the key earlier.
Dathomir was really well done though for the standards of Rebels adapting a Clone Wars location to Rebels animation.