Yeah, besides needing a new kind of system, how would you determine each set "limits" (or boundaries you know)? Since each set in BC is theoretically, limitless, tho after a certain range from the origin the bug known as "the camera shaking bug" occur.
Also you would still need to change the set, loading the next one and placing the ship there, which would kinda make the set you were in vanish and the new one appear, cuz (planets and so) in a single one for performance and positioning issues.
Finally, if you would take real system positioning and ship speed into account (like GC does), then you would need to account for the different distances between system so the ETA is appropriate. And well, to shorten this up, there's a reason for the ships to use FTL methods instead of regular impulse (which is sub-light) to travel from system to system lol