At the risk of dragging this discussion slightly off-topic, there are some things about FCs that bother me...
1. FCs surely have to be Open-only? I play in Solo exclusively and it will be utterly weird if this ghostly Marie Celeste suddenly showed up in my home system with no crew, no ships, no nothing. Contrariwise, look at the salt around Solo players impacting Powerplay and the BGS from the "cowardly shadows" of Solo. Now imagine the salt if FCs allowed a squadron to arrive in a system and deliver a force-multiplier to that gameplay. What could the home faction do to counteract it?
2. FCs must be persistent. How could it possibly work if individual squadron members are flying around a system, destroying local commanders, but then dock with their FC and suddenly disappear? Imagine the (justified) wailing if entire squadrons can combat-log.
3. I don't see a problem if FCs allow squadron members to refuel and rearm, as long as there's an economic mechanic in place to allow that (ie, no free fuel, no free ammo). Anything beyond that becomes massively problematical. So FCs can't possibly have a local market for trading - how would that work? What would determine the buy/sell price if the FC is 20kly from the Bubble? If they're buying, who are they selling to?
4. FCs cannot have an unlimited shipyard. As far as I'm aware, there's no mechanic in the game that allows commanders to be outside one of their own ships. If you're in the game, you're in a ship. The idea that individual commanders would be able to buy an FC and then stock it with multiple ships can't work with the current state of the game, unless FD allows you to transport a ship from a shipyard to the FC. That should be subject to the same cost penalty as normal ship transfers, and it should scale with distance.
5. FCs cannot have a UC franchise aboard. This is such a game-breaking pay-to-win mechanism it can't possibly be justified. If a squadron is 25kly out, it cannot be allowed to turn in exploration data for a 5/10/20ly jump to the FC while non-squadron commanders in the same sector have to jump 20 or 25kly to turn in their data. I believe that happens on the Gnosis but only because the Gnosis is open to everyone - commanders should be able to dock on any FC and use the facilities, or no-one should (including squadron members).
6. There's at least one commander on the forums who constantly refers to FCs as "Capital Ships". This cannot be possible. For the simplest case of balance across modes and gameplay, FCs must be no more than 'carriers' that transport 'fleets'. Unless FD is determined to gift Open multiplayer with illogical benefits, and essentially force players into cooperative Open mode, then a squadron of 25 should have no more benefits than are available to 25 individual commanders.