Most of the Others were killed last season, but the women and the children are, as far as we know, still alive. Most of the Others have been there since before the Dharma initiative, but some of them were either kidnapped or brought in from the outside world by Ben. So those few should, theoretically, be hopping through time. Although if we don't know what was happening to the other people from the plane (Rose, Bernard and all them) during the time traveling, I doubt we'll ever know what was happening to the Others.

Speaking of the people from the plane, do we have any idea how many of them are still alive? I know at least a couple of them got shot during the arrow attack, but I think they were just red shirts. Did we see if Rose and Bernard got away?