Manipulating Eternal Recurrence of Time by J.

I believe that we will see the "normal" cycle of time in Season 6 that is untouched by Jacob. We will see all our characters NOT crash on the plane, then our characters and others we have seen will be reunited in this normal cycle of time only to survive the destruction and pending end of time. They know that they will soon die too. Jacob will be with them and he will be their guide and help them plan how he will travel as far back as The Black Rock (and farther) and begin manipulating time and events in order to save the world. The earliest manipulation helped form the Monster. Jacob's nemesis doesn't want destiny changed.

The choosing of what events to alter also helps cause all the character connnections we've seen. The plane crashing was part of the plan. All this time manipulation caused all the discrepencies we've seen as well. In the normal cycle, Jacob was not bringing people to the island as we now know him to do. The Others are all in on the plan and doing as Jacob tells them to do. Ms. Hawking has been working hard to maintain these altered events and to help stop course correction. A course correction for the end of the world was about to happen til Desmond turned the fail-safe key. Seeing Jacob touch the others was him shaping different future events to occur. The version of Losties from the normal cycle are in the Temple (along with others who we saw die in the altered cycle, and all these people are probably the whispers), waiting as their timeline is altered. The Losties that are back in 1977--Richard will really watch them all die.

Children are important because a lot of them are being born or living in this altered cycle when in the normal cycle, they would not have had the chance to have been born or age since the world was ending. The Others are protecting them from course correction as well.