I am intending to run a multination Earth campaign set from 2030 onwards once the dust has cleared from v6.3's release.
I've considered a variety of formats, and having followed several of the community games that have been run have settled on a slightly less involved system, to avoid the problems that crop up with turn timing, etc. as the game goes on and conflicts and the like become more common. Essentially, the players will run their faction from a very high level (ie. 30000ft view style), with the majority of decisions being more about policy and planning than the specifics of implementation - those things will be left to your staff, which is represented by myself based on the characters (and their traits and history) assigned to various functions in the game itself.
In the normal course of things, the player would get yearly reports based on various aspects of their faction - military, economy, politics & espionage (run through a separate system in lieu of Aurora's built in espionage system, which will be reserved for use against NPR's only), and the like. A lot of this is just information, with significant events or decisions asking for input (for example, there might be two competing design proposals for a new ship design, which the military wants the leaderships opinion on), and these decisions will shape the future overall policy of the faction. A player could choose to receive more detail about specific aspects (ie. representing increased scrutiny/interest in specific functions) but this would come with the tradeoff of less awareness and a more passive approach to other aspects (essentially to discourage wanting extra detail on everything, which is of course likely to lead to slowdowns).
Key events like declarations of war, reports about first contact (not first contact itself - that would be handled by the commander on scene alongside the fleet commander if there is a comms link) and the like would result in 'midturn' interrupts and notifications. For both regular turns and these interrupts, there would be a certain period allowed for responses, after which decisions would be taken by your highest ranking character (typically the Administrator for Earth). If someone does miss the period and sends in something late, then of course I will try to correct the back towards those decisions wherever possible. Note that in this system all communications including diplomacy and trade negotiations would go through me, to allow for things like interception of messages by espionage teams, etc.
I intend to run a scaled down version of this system to test how well it works in a 3-4 faction setup, after which I will be looking to start getting players togeather for my intended larger campaign. That will feature 10 initial factions, with the potential for 2 more to emerge during the course of the game. The target would most likely be 6-8 players, as there are 7 major or intermediate factions.