In most Canadian time zones, this post is set to publish during the Lost finale extravaganza. Yes, I've been sucked into the vortex of the island, not because it's a particularly great show, week after week, but because I need to know how it all works out. Here's my take.
Some of the characters that are alive in the alternate timeline but dead on the Island, die, sacrificing themselves for the common good. There is a lot of punching and some gun brandishing. Everyone on the island dies in a huge explosion, and the island disappears forever. The newly exploded characters become themselves in the happy alternate timeline, and don't remember the island. We never learn why women who conceive on the island die if they stay there, how the island got there in the first place, why the DHARMA food drops continued in the present or how the Lighthouse (either one) was built. Some fans complain about the ending being too mystical and others complain that it had too much bogus science. Next television season sees a lot of new shows with ensemble casts, mysterious happenings and fist fights.
And with a little luck the polar bears (who will survive the destruction of the island by escaping to Tunisia) will figure out how to survive the melting of the polar ice caps. I think their main strategy so far involves interbreeding with grizzlies, who have the whole finding food on dry land a little better worked out.