My Thoughts. Would like input.

[Vanquish]

I think it's fair to say that exclusivity kills games and that having a small selection of very competitive clans amidst a sea of random pub players isn't encouraging the growth of the game.

completely agreed.
I think being part of a clan is the reason that most of the long-term players stuck around as long as they did. The trouble is, most new players aren't aware of the existence of clans, and the ones that are end up joining random teams that are doomed to live for no longer than a month at a time or something simply because their recruitment is inherently exponential rather than sustainable and the clan basically implodes as a result.
I still think raising awareness of the AC forum to people playing ingame would help a lot tbh, so that newer players could understand that there's actually a somewhat alive community out here who still enjoy playing the game, and that as an AC player, they should be welcomed to participate in said community in whatever way they can. I'm willing to bet that a significant number of public players don't even know about the forum's existence (I certainly didn't until like four months after I started playing or sth).