Ok, everyone needs to go back and rewatch all Desmond-centric episodes RIGHT NOW!
You know how my kids are watching Lost for the first time? Well, they are in the middle of season 3 and were just watching the fabulous Flashes Before Your Eyes where Desmond flashes back on almost asking Penny to marry him before Eloise Hawking (in the Jewelry store) talks him out of it and tells him he is supposed to push the button.
At the time, we didn't know much about the Mrs. Hawkins character. We all thought the only thing she was talking about was pushing the button and "course correcting" to make sure Desmond went to the Island. But, something she said stuck out to me as I watched this scene over again with my kids.
Right after she tells him he has to go push the button she says, "because if you do not do it, all of us will die."
Now, when I first saw this scene several years ago, I quite naturally thought she meant that his failure to push the button would kill everyone. But, in light of what has been happening in season 6 and especially what happened in this week's episode, allow me to posit that she does not give a rats behind about the button. She needs Des to go to the Island for the same reason she needs him to not look for Penny in the alt-world. She is trying to preserve some kind of destiny and reality. That is the "we are all going to die" she is trying to preserve. It has nothing to do with the button and everything to do with making sure that Desmond is in the right place doing the right thing so he cannot change reality in such a way as to destroy the world she is protecting/creating.
I'll even go so far as to say that she is probably somehow working with and helping FLocke/MIB. After all, she is the one who told Jack to bring Locke's body back with him on the plane (allowing MIB to take his place as FLocke). She is now the one trying to stop Desmond from alerting everyone that "something is wrong" in the alt-LAX (which will probably cause folks like Sawyer and Sayid who are on MIB's side to abandon him or something like that).
Hearing Eloise say, "or we will all die" just struck a real chord with me. Is it possible that the end game we are seeing right now was being foreshadowed back in the middle of season three?
--Jason "by the way, Eloise can see people's fate before they die too-- just like the way Des did with Charlie" Evans