Fly the Line is currently focused on the short haul airline pilot experience, and returning to the hub airport at the end of the day is a core part of how the career mode is structured. As JMAviation has correctly said, on 4-sector days, you may be given routes such as A-B-A-C-A, or A-B-C-A, but you'll always end up returning to the hub airport at the end of the day.
This is all useful feedback to us, though! Fly the Line will remain supported for a long time to come, and feedback such as this is being logged on our internal trackers as possible areas for expansion/improvement in the future.
Mark - Just Flight