Just think the scene of Sayid going to kill Desmond. Isn't this familiar to you ? It's exactly the same as MIB sending Richard to kill Jacob. And both Sayid and Richard do it for their loves. Interesting !! What did Jacob give Richard ? Immortailty. I think Desmond gave Sayid immortality. And he was replaced for Richard. So we may see Richard's death soon. Desmond became Jacob, Sayid became Richard, Jack will become (I think) MIB and Claire became Rousseau. Now the new circle is about to start. Maybe Desmond is touching people because he will bring them all to the island. They will come again with blank slate.