Can I join? I only started watching lost in January so have done 5 series in a few weeks
I think the plane/airport scenes are an alternative timeline rather than a flash forward (I think Jack recognises desmond from the stadium) but haven't figured out how they are going to reconcile the two and how they are going to tie up all the subplots (eg did Penny's parents get off the island so would she ever have been born, would Desmond even have been training there if not for Penny etc)
I think Rose and Bernard will prove to be significant characters, remember they also didn't want to leave the island and that the island cured Rose as it did Locke. Also they were annoyed when the rest of them found them in the 70's flashback-just don't know what yet!
Sayid imo will be the new Jacob, maybe Jacob is in him but most likely his role has been passed on to Sayid-throughout the seasons the recurrant theme has been Sayid regretting his past and wanting to be a good guy. As long as he doesn't put a top on I don't care
The thing that most confuses me is who the heck the Others are and what their role is-I mean Juliet and even Ben seem pretty clueless yet at various points they have been able to kidnap/attack without even being seen or heard. Then at some points they are wandering through the jungle with bare feet and rags on, other times they are doing high tech research etc and wearing high heels (and then you have John Lennon the hippy types in the temple)
It's all just a big headfuck! No doubt my theories will have changed completely by next week...