Charlotte: "I'm gonna stay, Daniel. For now anyway."
Daniel: "Charlotte - There is no for now. If you don't come with me now, could be forever."
Charlotte: "Nothing's forever."
I'm guessing most of us just passed this off as indication that Charlotte didn't know what Dan knew - that the guys down at the Orchid were about to move the island - in time. But I've re-watched this scene a few times and I'm now wondering if the writers are telling us something here.
What Charlotte knew
After all, Charlotte was aware of the fact that the island has strange time properties, and probably that the island was always jumping around in time, on a small scale. This is evident when she tells Dan not to confuse everybody when Jack and Juliet asked about why they're unconcerned that the helicopter had been gone for so long. So it's likely that Dan shared most of what he knew about the island's time problems with Charlotte. Therefore I'm pretty sure that Charlotte knew what Dan meant when he said "If you don't come with me now, could be forever."
So what does her reply mean? It could be a hint to where the all the time-travel in the show is leading. We keep hearing over and over, "Whatever happened happened", "You can't change the future", and "You can't change the past". Of course those are 'the rules' (at least in part). Only, a story in which everything is fixed and nothing can be changed (especially when the audience knows so much about the future) is a dull story.
What are the rules?
I'm beginning to wonder if there are other rules we don't know about - rules like "Nothing's forever", meaning that "Whatever happened, happened... but it's not carved in stone to last forever. Maybe whatever happened, though it did in fact happen, can be undone. This could be the key to the problem of logic-defying self-induced chicken-and-egg time loops.
Now let me just state for the record, I'm not advocating alternate universe theories or paradoxes. I can accept that in the Lost universe, course correction keeps things from changing too much, and you can't go back in time and negate the reason you went back in the first place, etc...
What game are they playing?
But I have heard some interesting theories about Ben and Widmore playing a time game which they've played before. This theory seems to fit the best in terms of creating a suspenseful dramatic story-line. There has to be something at stake. Something that depends on the characters, which they can change. Otherwise it's just, like I said before, dull. It would also explain the need for temporal policemen, like Hawking. If the universe automatically course corrects and you can't change the past or the future, then there would be no need for temporal policemen or people like Abbadon who "helps people get where they need to be". All that would happen automatically.
So it seems pretty clear that things can be changed, at least by "special people" such as Desmond, and perhaps by all our time-traveling Losties. What the limits are on this possibility remain to be seen, but one possibility is that you can change anything, but the consequences could be catastrophic. Maybe if you just change small things, the automatic course-correction kicks in. But Mrs. Hawking's note of alarm in her voice when Desmond insists on buying the ring makes me think that she and Abbadon are there to make sure no one goes too far off course.
Why? Because if they do, then "God help us all". Could it be that this whole loopy time game thing is not to change whatever happened, but to stop someone from changing whatever happened? Maybe the purge was not in the original plan. Maybe Locke wasn't supposed to die. Maybe that's why the Island could reincarnate him. Maybe that was the course-correction. If Ben's whole life was messing up the timeline, changing the past, the future, from what had really/initally happened, then our Losties may be the island's way of inducing course correction on a grander scale than is built into the universe.
What really happend?
If the island could reincarnate John, then what else can it do? Perhaps reincarnate the Dharma Initiative - back in their time. The Comic Con video hinted that there was a bigger purpose for the DI and that the fate of the universe rests on their success, but that the purge interfered with that and now the universe is in dire straits.
It is a war of fate vs. free will and I'm gonna guess that free will is more powerful, and that the fate of the world doesn't drive, but rather depends on the free will of the Losties, Ben, Widmore, etc. We've seen time from the Lostie's perspective. From Dharma's perspective. From Richard, Charles and Ellie's perspective. But one perspective we've never really seen is Jacob's. I'm gonna hazard a guess that his is the one you need to see to know whether "whatever happened" was what initially happened, or whether it messed up whatever really happened.
What's up with Jacob?
I'm also gonna guess that Jacob's existence has been in a way 'negated' by someone's errant meddling in time. But since whatever really happened involved him in some way, he couldn't be entirely driven out of existence. So he exists as many have said, out of time. He can't exist in the normal timeline because whatever happened was changed. Perhaps by Ben... This would also explain why Ben is the only one who can talk with him directly. Locke can't see Jacob the first time, and when he visits the cabin a second time he talks with Christian instead. But Jacob's plea for help suggests that Locke needs to fix something - something that was Ben's fault. I don't think Ben just fell out of favor with Jacob. I think he actually caused Jacob's predicament. And I think Jacob finally found someone who can reverse the damage that Ben had done and that had knocked Jacob out of the timeline.
But here's the catch - I'm pretty sure that the universe is finite. As long as time is still in motion change is possible. But if something has been changed for the worse, and it is not corrected in time, then the end of the world will arrive and it really will be forever.
But for now, and as long as the world is still spinning and the Losties are still living, nothing is forever.