Eh, my impression of Lost is that they had a general idea of the direction things were moving in but had no idea how to work out the details. There are some clear predictors of things that happened years later when it comes to the major things. For example, in season 2 when they first enter the hatch, Sayid remarks that cement was poured over everything, just like chernobyl. They wouldn't have tossed that in if they didn't know a nuclear bomb had been detonated there. And earlier actions taken by the black smoke monster make more sense once you know his history.
But on the other hand, I'm absolutely certain they originally had Walt as the main candidate, before the actor grew so much. That's why they set him up to be really good at games and always using the white piece.
But on the other hand, I'm absolutely certain they originally had Walt as the main candidate, before the actor grew so much. That's why they set him up to be really good at games and always using the white piece.