Let's say if every single members of the big organisations are active, how many of them are there because their organisation is the biggest and the strongest?
And how many will jump ship after their nation's first defeat in pvp when they realize they won't dominate the universe? ?
From my experience in mmorpgs like Black Desert, which is basically a 100-members-guild based game, 50% of the top organisations split, disband or just disappear within the first three month and the new ones rise, so don't worry if your organisation only has 2 members right now, it only matters three month into the release! ?