I don't think for one minute that Mark died. I believe that Lucas told Mark that he would die in order to save him. I think the person in Charlie's FlashForward is Mark. Mark Benford very well can be alive. there was a hellicoptor outside where he was running to just before he blacked out. The people in the helicopter may have a QED ring on because there is 7 known rings and as we know only two were being used during the second global blacout, the one that Lita had on, and the one that Simon and Demetri had.