They will do either one of the following:

1) you decide the change is too drastic and dont want to take the trip any more. miles go back to your account and re-depositing fee waived. However, if you booked this initially over the phone, the phone charge is NOT refundable, no matter what. As much unreasonable as it seems, there are lengthy discussions and threads in various manners, in airlines forums - that very few has been able to recoup the phone booking fee.

2) you still want to do the trip and the agent would work with you to find alternative routing to accommodate you. The change fee is waived in this case.

Either one position you took, would be documented and is considered case-closed once that is done.

You cannot therefore change your mind afterward. Of course, if there are NEW schedule changes in the future before your traveling date, it would be treated as a brand new case, with the above options once again.