T3 and Hk47 seem like they are going to be around and have a sort of r2 c3po thing going. As for the other characters i dont think that juhani, jolee, mission, or zalbaar will return to not cause conflict with the darkside ending. Carth should return given that you do go to his home planet. i dont think bastilla will return either but they could probably include her if they wanted to. Canderous should return though