Kh2 last Cutscene explination?

Can anyone explain the last cutscene in kingdom hearts 2 where Terra Aqua and Ven take the kingdom key, reverse kingdom key and way to dawn? it doesn't tie in with the ending battle with Xehanort and Vanitas because they dont have the keyblades... I have a theory that the walking figure when they pick the keyblades up, the figure walking towards them is sora, which would make sense with the secret ending to birth by sleep and all thats happened. Aqua gave her heart up to save Terra and she ended in the realm of darkness and met Ansem the Wise, Ven's heart was destroyed because he destroyed the X-blade and Vanitas, Terra's heart was taken over by Xehanort and formed him into the guardian heartless which Xehanort destroyed in bbs. so it would make sense that their lingering spirits would stay in the keyblade graveyard awaiting sora to free them from their torment. < my theory for that cutscene. Can anyone shed light on the subject?