There's a difference between "ruling" her people, and being a leader. She explicitly says she will speak on their behalf (which what leaders do, mind you) - but that she won't rule them, referring to Calia for that instead in all likelihood. She's still going to be an active voice in the leadership of the Forsaken, and until Calia does take up the proverbial crown she's their racial leader for now. What may happen in the future remains to be seen.