Henry Ian Cusick is on board as a main cast member for Season 3. This means much more Desmond, which is clearly awsome, because he's great.

I don't believe either Harold Perrineau Jr. or Malcolm Kelley have been signed up for Season 3, so it could be left up in the air for a very long time as to whether they genuinely got away or not. You know how The Others are - they could have quite readily steered them towards absolutely nowhere.