In Guild Wars 2, players can be members of multiple guilds at the same time. A player can only represent and chat with a single guild, but with a click of a button they can change their allegiance to another guild and chat with them. Access to guild perks also switches with the allegiance flag. Right now a guild can eventually contain up to 500 people, I believe, although you have to buy “membership expansions” in the cash shop to do it.
The multiple guild membership hasn’t been tried in any major MMO before that I know of, and I’m pretty interested to see how it effects player socializing and migration. Overall though I can’t see any reason why one wouldn’t want to be in the largest guild possible for the three-faction realm vs. realm battles.
Based on the planned rotation and the nature of the battles it’s not unlikely that at some point your server will be engaging a superguild, whether it’s Goons from Something Awful or Alea Iacta Est from WoW’s Earthen Ring or, god help us all, Reddit. Being in your tight 5-man “family guild” is going to be an exercise in dedication when your disjointed realm is having its face pushed in by a semi-organized zerg for two weeks. A server made up of many small guilds is going to be at a serious disadvantage.
Additionally, a guild designed from the outset for WvWvW can focus on specific perks that help in those specific situations, unlike a smaller guild which often has to also suit folks who like some PvE or crafting or whatever. Having more people in the guild will get those perks even faster, so even if a smaller guild does focus on realm battle perks the giant guild will have them much sooner. This will obviously equalize over time, assuming there’s a cap on perks, but it seems fair to say it will be pretty uneven for at least a few months after launch.
I actually don’t know if it would be significantly easier to organize a group for either zerging or individual tasks as part of a guild, as opposed to just using the equivalent of realm-side general chat (there is such a thing, right?), but it sure wouldn’t be more difficult. Arguably having some kind of leadership structure in a guild might inspire folks to follow directions better, although that’s definitely not necessarily going to be the case.
In short, I don’t see any reason why people won’t start congregating in one or more giant guilds for each server strictly for the purposes of WvWvW. The only exception would possibly be smaller guilds of highly skilled and tight-knit PvPers, but as Spinks said in her post today, casual players generally like zerg PvP because “joining a zerg is a good way to take part in stuff without it mattering too much about your specific build.” I suspect trying to participate in the realm battles as part of a small, casual guild will be an exercize in frustration, or at least frustrating enough that most folks will choose the easier path.
If one was interested in gaining a reputation as a PvP leader type in Guild Wars 2, my advice would be to make a realm-PvP-only guild on the first day and start inviting everyone. We’ll have to see how it plays out, of course, but in theory it seems to me that big zergy guilds in WvWvW will be the optimal way to go.