It would be nice to have that AI not dumb ships wandering around sectors, but a real traders, pirates, mercenaries...really. I would expand it not to just build ships or stations, but to have them live their own life. Tradind guild would salvage asteroids and such, pirates would try to intercept them and take them cargo when the battle begins... or would the trading guild just surrender? Players would have chance to save trading guild, which would earn them some bonuses from it, or to just let pirates take damage and salvage what is left of anyone after battle ends. The stations wold be also trading guilds posts, from where it organizes its struck for resoursces. capturing it almost intact would let player get most of ships docked inside as well as its storage.Pirate stations will get the storages filled too, but mostly with contraband and such. having bad reputation with one of them will make you wanted person, and AI ships would time to time try to get you and take reward. Maybe even players could complete the mercenary work? The whole concept of this is to let space live even without players.
To the aliens: I like the base idea, but you are forgiving about some minor factions of 3-10 players. The AI has also to calculate how big the ships would be, and how much of them.Or dont target them.The fun would be that players from whole server will gather and try to destroy that Fleet, which target home of one Major faction. About 150 Players at one place may lag servers, but the fight would be epic.
The Mercenaries said about are one big great idea. having AI ships join your ships in invasion for some time by just gettin\' payd would make the faction economy boost towards race for bigger mercenary fleet. maybe you could hire them at stations, where rare types of mercenaries would be find at pirate bases(like marines and frigate/fighter operators are foud almost everywhere, these would have to be squadrons of cooperating corvettes or an entire battleships) this would require a AI player-like entities to be implemented into game, but Im sure that this is something that you cant just leave out at something like StarMade.