Appartments
While I agree it could add some focus on the kind of goals you want to create for yourself, I'm not so sure this game will allow a lot of hoarding (as in having a more limited storage space on your suit and ship, so even if you find a large deposit of minerals, you can't carry them all in one go), but I could be wrong. Seeing as how you have a save/respawn point in some of those buildings, that's pretty much enough to keep you somewhat safe from total progress loss, so you could just park your ship outside the building or nearby and explore and gather on foot, come back, unload into your ship or trade with an NPC or hop to the nearby space station, come back etc.
Central Bank
I was under the impression you get ship upgrades by finding recipes, crafting and then placing them in your ship slots, if you have room? If that's the case, that's plenty of restrictions right there, and I'm not sure what the problem is with carrying money, since as I understand it, you don't loose cash when you die anyway, it's always safe (well, unless you spend it all on a shitty ship
).
Hydro Boosters / Submarine / Land Vehicles
Sure, and as an alternative, you could also have your actual spaceship be a transformable vehicle, so it does it all - space, land and underwater, so you wouldn't have to carry a second ship inside your cargo bay (I guess Elite: Dangerous does that with the buggy), and you wouldn't be restricted to having the ability to carry a buggy/submarine only for larger trader ships, since every ship would be transformable, but that adds a lot of complexity to the procedural ships system, so it's doubtful. Or, the devs could just conjure up a silly box that's "bigger on the inside", a Pokeball of sorts that just springs up your buggy/submarine anyway.
The trouble with adding land and sea vehicles post release is that, depending on how they're handling the size and depth of the water surfaces, if there are massive underwater cave systems etc, we might get a huge procedurally generated universe where there are no huge underwater cave systems or large or deep enough oceans, so that suddenly adding a rather large-ish submarine would make the whole thing obsolete. You wouldn't be able to enter those underwater caves or the oceans might be a bit too shallow (although I doubt it), because the game was designed and the world generated beforehand with on-foot, human sized underwater exploration in mind. The "hydro booster" to the suit would work well though, and I wouldn't be surprised if there isn't something like that (an upgrade that speeds up swimming/diving) already in the game.
I suppose having land vehicles would be more easily implemented, although there would be some risk of getting stuck a bit too often, but that's kinda solvable in various ways. It would however mess with the general gameplay loop of having your spaceship as an "anchor" while exploring the environment, since I think the idea is to land, look around a certain radius near the ship, come back, get in, fly to a different spot, repeat. Can't remember if they mentioned a "call back" feature, bringing the ship on autopilot to the spot you're standing at the moment, maybe as an upgrade?
Anyway, I'd say that any updates to the game post-release will be more oriented to adding, or rather "enriching" already existing gameplay systems. So something like adding new meaning to the consequences of destroying a space station, for example. Like, you now have the option to choose to work for the malevolent force and erase the presence of all other alien races in the galaxy, so the more space stations you destroy (they might also add new weapon recipes, expensive weapons that deal massive damage to stations), the more you see the alien factions just stop appearing, more derelict stations, on planet buildings that were once occupied by NPCs would be empty (so you'd "sabotage" yourself by not being able to trade in that system anymore, but your "evil Sith allegiance" progress bar would fill up, giving you more money, special tech and whatnot. On the other end, you'd also be able to help the factions in more meaningful ways, like investing cash in better armor and shields for their space stations, more defensive manpower, selling star system exploration data to make their expansion into new systems (simple stuff, like you now see a new space station in a system that had none). And all of this would be visible as some sort of power play percentage on the galactic map screen, so one half of the players would, if they so choose, try to destroy all life in the galaxy, while the others would defend it, and doing all of that without even needing to ever meet each other, so no change there.
Also, they might scatter special items throughout the galaxies, new artifacts, recipes, macguffins that are kinda hard to find (but doable if you have the right equipment, scanners, follow the hints), even scattered on planets you've visited before, so it would be a community effort to analyze these items and upload the data to the Atlas, so the more people find these items, the more info you'll uncover about the new "season 2" plot, unlock new types of weapon upgrades, get the ability to instantly travel between galaxies, grander scale superpowers etc.
And also maybe even implement some sort of multiplayer, joining groups of friends in their own multiplayer lobby who are always traveling tethered, together, all hyperjumping at the same time to the same star system, always be able to find each other and maybe even hyperjump/teleport more easily to one another etc.
I didn't think this game would be the kind that would get stuff like this added in future updates. Have they talked about this kind of thing?
Sean's mentioned a few times that they want to see how the game is received, if it sells well, what features the players will want the most, so they'd like to add new stuff to it.