The obligatory comparison with this game and World of Warcraft would note that in the new expansion for WoW, all normal raids are being turned into "Flex Raids," which means you can take anywhere from 10-25 people, and the raid scales with how many people there are. Obviously you cannot simply add flex raiding to old content (imagine 24 man turn 7!), but you can design new raids with that system in mind. Please consider creating the normal tier of raids to be flexible, so that we aren't restricted to a hard 8 person cap! My personal belief, is that while flex raids tend to be more difficult to balance, it is outweighed by the ability to play with your friends, regardless of your group's size.