We've seen in all the flash sideways that the characters are similar to their 2007 counterparts. Their circumstances may have changed but they are still the same in regards to behavior, attitude, morals, etc. What I mean to say is that their core personality is still the same. For example - Sayid is still a murderer/torturer, Jack is still a surgeon who has had many issues with his dad, Ben cares very much for Alex, Claire is pregnant and so on.
What if the purpose of the flash-sideways is to show us that no matter how the circumstances change, the characters will still remain the same?