Mesh As it stands now, a shaman is a better group healer than a druid in most situations -- and in all situations where you don't have another slower.
I also think you're fundamentally wrong to claim that the game is built for "ideally one healer and one support per group". There is NO dedicated "support" class, nor would any group take a class that did nothing but "provide support". The reality for "ideal" group content is more like:
Easy grind content: 1 puller, 1 tank, 1 priest, 3 DPS
Tougher content: 1 puller (maybe), 1 tank, 1 priest, 1 CC, 2-3 DPS.
Very tough content: 1 puller (maybe), 1 tank, 2 priest, 1 CC, 1-2 DPS.
Most classes provide some level of "support" -- but they also have a core function that is NOT support.