I’m sure somebody has already suggested it, or possibly Anet is already working on it and I didn’t know, but I was thinking that it could create a sense of sport in a guild when they compete each other for guild-wide prizes and such and such. They could have it so only 100 or so could compete from a guild at once, alliances are allowed to fight as one, and everyone is boosted to the same level. In such a PvP they could give each guild a keep or two and put them on a mini-map, not as small as PvP, but obviously not as big as WvW. Guilds would be a much more organized form of warfare as well, giving better strategy than WvW or PvP.
Any other suggestion, criticism, or correction to this is appreciated.