In some cases you need 80 or 120 members for next clan level.
Basically this means you will see about 40% less clans on Lionna and more bigger clans.
The whole academy thing needing to get noobs in there to level your clan is not gonna work unless NCSOFT finds a way to bring a few hundred noobs per server into the game come C5.
You're not going to see fewer clans - people will just put alts in subclans to get points etc...
As for zerg - lol - who cares if you could have 1000 people in a clan - you still have to find those people. Unless we eventually see a server merge (which is unlikely because of clan halls and to a lesser extent castles) the numbers aren't going to change dramatically and if anything will diminish over time.