I know we will get a fourth season. I read somewhere the actors have been recording for one since July. I know Bo-Katan will be the leader, because I know she will appear later on.
It's just like with Admiral Zhao from Avatar: The Last Airbender. Notice how both characters have the same voice actor and how their roles and characters are very similar. Both are the main antagonist if season 1, they duel during the finale, and they both die in the same manner--they accept their deaths because they don't want to face the wraths of their masters. So they're also similar in that they're both killed off during the season one finale, and are replaced by someone worse, much worse.