What if Faraday was wrong?

Do you remember Desmond and him seeing the future after the accident in swan station? Faraday knew that Desmond is special. But did Faraday knew that the accident happened to him and that he saw the future? If he didnt, he could easily made a big mistake by telling Jack to detonate a H bomb with high level of magnetism. The fact is, that this changes a lot of things. This one simple mistake can maka a big difference.
lets say that the plan would work and H bomb will bring oceanic 815 to Los Angeles. What would happen to the island. I know what you probably think. Dharma is back Linus is leader, Jacob is still alive, there was no plane crash. But what would happen with magnetism in swan station. It would be much stronger than ever.
Lets say that the plan wouldnt work: If that happens we can easily see Al of them on the plane and then in one moment back on the island. Yes, i know the skipping was already used. But in reality there is no other possibility.
As far as we know they can all be dead, but they dont realize that. So if they use anything else that is no more science fiction show but totally one big mistake by the writters.