before they base sprawl on sectors they need to find a way to keep your empire from spawning weird little zones where you have like, 6 sectors that consist of one or two systems each
Or at the very least the ability to redraw/remake sectors. For example, by nominating a sector capital that will then take every system 2 hyperlane jumps away to join that sector, either taking said systems from non-core sectors in the process, or by being able to make a planet go 'sectorless' for an extreme penalty that means you'd want to only use it as a transitory period as you redraw the sectors.
Or allow you to manually draw sectors yourself to keep things pretty, with the stipulation that no colony can be further than two jumps away from another colony in that sector, and be at least 4 jumps away to all colonies in that sector (essentially the same sector size and method of spawning in game, but you can add those annoying rogue empty systems to a sector for your sector map aesthetics).