1.a. It was suggested in this thread of conversation that the dead person in the coffin was Michael, because the funeral home was located in an African American neighborhood. I thought this was a great observation. However, the first thing I noticed was how small the coffin seemed, suggesting it was a child. And since Walt (Michael’s son) keeps appearing to people on the island as a ghost of sorts, I think it might be him. Though I can’t say why Kate would be indifferent to his passing.
1.b. Before reading this thread, my prediction was that it was John Locke, and Jack was devastated by his death because he thinks Locke was right about staying on the island, and Kate was indifferent because she doesn’t agree with Jack and is bitter with Locke for creating so many obstacles in getting off the island.
1.c. I’m also holding on to the the possibility that the person in the coffin has not even been introduced to us, that it is someone we will learn about next season.
Which brings me to my two possible predictions for next season:
1. The rescue they are awaiting doesn’t happen right away (or one week on the island stretches out for an entire season. I mean really, in three seasons they’ve only been on the island two months, right? so it’s possible the next season will be a shorter period of time). And instead of providing flashbacks to give clues, we are now going to see flashforwards, and we have to figure out what happened on the island by interpreting how it all shakes out after rescue.
2. They do get rescued, and the majority of the show is seen through their new lives, and we have no idea what happened to them on the island. We will now see a series of flashbacks to the island to give us clues about what happened.