Since the actor who played Ethan is now a semi-regular on "Threshold," it would be rather unusual for him to return to "Lost" unless he's one of those actors lucky enough to get two relatively important roles in one season.

__________________
Things fall apart, the center cannot hold;
Mere anarchy is loosed upon the world,
The blood-dimmed tide is loosed, and everywhere
The ceremony of innocence is drowned;

--Lines 2-6, "The Second Coming" by Wm. Butler Yeats