There will be limitations on the numbers of guilds and the number of active players in an alliance and an alliance will bea smallish percentage of the total players of a world. Except: " Our current plans for alliance size are somewhere between 500-1000 members"and: "Because of this, there are plans to allow transfers between worlds during a season. This means that new worlds will have size restrictions on them, as they do currently." but a server cannot be x-ferd to unless the active pop drops below 90%. 91-100% is all you need to completely lock down a server as "invitation only". This new system will not add structure to WvW but give players far too much control over it and certain players will take advantage of this.