[Reed]

I like this theory and I hope this is the case, purely for Danielle however.

The corpse did not look like Danielle in my opinion. The Freighters would have quickly rushed over to capture Alex and they probably inspected the bodies, which does not support this theory.

I think her story as LL stated will be told in Flashbacks because her story is surely one of the biggest in Lost.

Ideally, I would like inexperience/clumsiness as to why the Freighters did not check whether Karl and Danielle HAD died. As for why the bodies were covered up, it adds to the illusion that she died. God knows where she found a replacement body for her own however. I think a suprise appearance in the Finalé by Danielle is not far fetched at all.