Dont forget though, that blizzard is coming out with the drums, that can provide various buffs if you dont have the classes for them. So an all druid guild could do somewhat well in raids,
the drums do stack, and cover the majority of the buffs in game.
All druid premades would be interesting though. Lots of potential healing and burst. Imagine an AV with 15 boomkins running around spamming moonfire....15 ferals pouncing the sh*t out of everything and ripping, and 10 restos hot rolling on everyone.