Wasn't it said a long time ago that the second expansion would be diplomacy-related?
I think the next expansion should include espionage, getting planets without having to use a fleet. Piracy will no longer pay as the areas thicken with defenses and they will probably hire out as mecenaries to support fleet operations.
Personally, I think it should go the opposite direction. Make pirates a real, persistent military threat, the kind of thing that doesn't just become a nuisance in the late game. That means:
> Pirate bases would be HARD to neutralize. Not just a ring of gauss turrets; make their base act like a fully-upgraded starbase, give them some custom turrets (say, a "heavy turret" that's far more damaging and durable than a gauss turret, to make up for the fact that they wouldn't use hangars) and layer the well in minefields.
> Pirate capital ships. Only seen if the bounty gets high (say, 2k or more), with the level of the capship dependent on the size of the bounty. No fighters, light shields, low HP regeneration, but high armor and HP, with abilities stolen from all three races (not just TEC clones).
> Pirates shouldn't target just one empire every 15 minutes, which just leads to a flurry of spending at 14m59s. In any given minute, there should be a small chance of a pirate raid targetting EACH empire based on its CURRENT bounty. If two empires get into a bidding war, they'll both get smashed, and you won't be able to predict when.
> Pirates right now target a single planet, beat up that planet, and either leave or are destroyed. It should be more of an ongoing process; if the pirates bring far more of a fleet than a single planet can handle, part of it should split off and head for the next-closest planet of that empire.
Make it possible to turn pirates into a very significant late-game threat, and you'd have a very different play experience. It'd be possible to actually "win by proxy" by continually paying pirates to beat up on an enemy, without sending in your own fleets until it's time to colonize his now-empty systems.
I also would like to see an expansion focus on the economic side of the game. That is, we've got tons of flexibility in how we set up the defenses of a well, with a half-dozen defensive structures, a starbase, and minefields, but on the logistical side, it's a lot more limited; you put a trade post, a culture generator, and maybe a refinery or some research labs, but they're very interchangeable. Once you have 8 of each lab in your empire you never need more, and for most of the structures there's no difference as to where you place the structure within a well (trade posts being a minor exception). And most of the structures only need one within a well; front-line systems could use multiple culture generators, but that's a waste in back-line systems, while trade posts beyond the first are basically used to fill out whatever logistical slots are left over after everything else is bought. Starbases can have a couple non-combat benefits, but I've rarely found those to be worth the drop in combat performance.
That means we could have:
> Abilities on logistical structures that are position-dependent. This'd make their placement important in the same way as adding abilities to hangars in Entrenchment made their placement non-trivial. For instance, an ability on refineries that improve the production rate of any asteriods within a certain radius, or a culture center ability that gives nearby warships twice the usual culture benefits, or a trade post ability that lets all friendly trade ships move more quickly when near the post.
> A new non-combat cruiser, let's say the Mobile Refinery, that harvests additional resources for your empire from nearby asteroids, including enemy-controlled ones, by spawning small extractor ships that fly to the various asteroids within that well. Give it some remotely combat-oriented use as well, like placing Sensor Buoys (give you line-of-sight to that system and are phased out like a minefield), and possibly allow terrans and advent to use it to tow their starbases at very slow speeds.
> Additional research labs beyond the eighth provide other benefits, like a progressive increase to research rate. Labs should also have some local benefit, if you buy certain upgrade techs. For instance, logistical labs might upgrade to double as Orbital Farms, adding to the population cap and growth rate of their planet, while weapon labs might upgrade to double as repair docks or reduce planetary bombardment or something. As with the other things like this, it should vary by race.
> It'd be nice to have a new structure for each race, although this is UI-limited; Vasari, for instance, just don't have room for another logistical structure.