Long time lurker here, 1st time poster - so please be gentle. :)
OK - I love reading these theories and just had to give my 2 cents on all of these "candidate" theories. First, for all you "Katers" (Kate-haters) out there (those fans who - for whatever reason - just seem to loathe Kate, please keep an open mind and don't immediately dismiss this theory based on your personal feelings toward the character or actress). Second, TPTB are famous for revealing plot details and answers to mysteries indirectly. In other words, show the viewers and fans one thing and reveal the opposite or "hidden" details for a bigger reveal.
So here we go...the moment we saw the list of names and numbers in the cave, the theory boards blew up with this interpretation and that possibility along with one big question - why was Kate's name conspicuously missing from the wall ? Even on Dark's banner, the names and numbers of our favorite Losties are there along with a picture of sad Kate saying "But he TOCUHED me" ! (Which is hella-funny btw!) My theory - then - is simple. Kate's name IS there on the wall. Obviously the only names and numbers the TPTB showed us was what they WANTED us to see from the dim light of Sawyer's torch. Knowing that the fans would screen-cap this scene to death (duh, of course, we did), Darlton wouldn't purposely show us any ultimate answer right in front of us, right ? They're WAY too sneaky for that.
My thought is Kate's name IS there on the wall..somewhere. You gotta figure we could only see and read SOME of the names on the ceiling and wall. Did anyone else notice how BIG the cave was and how many names were there ? What makes everyone believe that just because we weren't SHOWN Kate's name means it wasn't there at all ? That's just what they WANT us to believe.
The big reveal will be that in the end, all of our Lostie's names will slowly get crossed off - being killed off (as we've been led to believe, this will be the "death" season and many of our Losties wont make it to the end). In the end, another cave scene will take place with a torch illuminated revealing "Austen" as the last uncrossed-off name as she becomes the new Jacob and protector of the island.
Remember - originally (if I'm not mistaken) - Jack was supposed to be killed in the first episode and the series was to feature Kate as the main "heroine" and Lostie leader. Well, this would be a way for the series to come full circle to its original premise and vision.
So - shoot away at this and give me your thoughts...