Here's my theory on eppy 100: The only people that are not in the present-day Superman world are Lionel Luthor and Chloe Sullivan. In some incarnations, Jonathan dies of a heart attack (TAOS series and STM) but in the present day, post-Bryne world, both Jon and Martha are alive and well.
Therefore....
I believe it will be Chloe (someone he loves) and Lionel (perhaps Jor-El takes over his body to fight Brainiac and wears it out???)
Chloe dying will give Lois impetus to become a reporter and Lionel's death turns Lex to the dark side forever (because he believes that it has something to do with the "aliens")
Unfortunately, these are the two of my favorite actors on Smallville so this will really SUCK if it happens!!!
