Heh. I already told them what i want for a DLC in a recent survey I filled out.
Give me internal politics: I want factions to matter more. I want genuine rebellions and civil wars to be possible. I want sectors to be able to break away and form their own nations -- possibly because a certain faction (or factions) became dissatisfied with the central government and came to dominate said sector.
I want leaders to be tied into all this as well especially sector governors and admirals. I want them to have some sort of "loyalty" rating, which can be affected both by events, but you can also do things to raise & lower their loyalty. Maybe a sector splits off from your empire because of an unhappy and/or ambitious, greedy governor. Maybe your army and navy splits during a civil war, due to some admirals & generals experiencing mixed loyalties.
I realize this is all a big ask of the developers, but hey, a guy can dream...
Also: As part of the accompanying free update to this imaginary DLC I'm conjuring, players should be allowed to customize their own sectors again, for Christ's sake. I'm sick of the internal border-gore.