The OP has me confused by saying FCs remind him more of a social group than a guild.
That's all FCs and guilds ever were - social groups. Like-minded players with similar interests and compatible personalities come together to do things. There's no requirement that specific content must be done.
If FCs aren't doing the content already in the game together, it probably won't be different with any other content SE choses to add.
Sure there is. It's not a solo decision on your part. You don't get to just walk up to people and say "I've decided I'm in your FC now".
Someone already in the FC with the correct permissions needs to invite you to join or accept the application you submit. The same person (usually along with several others) also have the ability to kick you from the FC on a whim if they desire. That leaves you at the mercy of someone's willingness to invite you and the FC's willingness to keep you as a member.
FCs are not a core part of game design. No one is guaranteed a spot in a FC simply because they created a character. They're an optional part of game design. You can play the entire game without joining a FC and miss out on nothing of importance. Even most of the FC actions (minor QoL) are available through Squadron Manuals.
FCs are perfectly capable of creating their own if they feel there is a lack.