That will be Kates nasty step dad who she did not kill in this new time splinter. So if you think about it Kates life its probably alot better in "this" time splinter hence she will be very keen to stay put.

Remember the reports of the place crashing and being at the bottom of the ocean - well that did happen in this in this splinter and killed them all which means coming back to this time splinter is easy for them as they won't bump into themselves LOL !

I reckon the next series won't be based at all on the island at all (well apart from the first one or two of them being rescued etc). It will show all the characters lifes now, some worst, some better. The interesting part will be how it will explain how the exact same people end up on the same flight in the two different times splinters - like the whole reason Jack was on the flight was due to his dad's death, well in this new time he is quite clearly still alive so why did he ever get on the plane!

Perhaps season 4 will end with them just about to reset/go back in time and I reckon desmond (he has already lived july two/three times now..) is the key to it all.

Anyway that's my take on it - probably bollocks and all wrong...!!!LOL