Sequencing Depth and World Cup Paninis

The World Cup is underway and I am back to the blog!  I was recently inspired by the World Cup Paninis to write a post about sequencing depth.  In sequencing, the problem we are often faced with is whether or not enough sequences have been generated to be representative of a population.  Tools we often use to determine whether we have sampled enough are rarefaction curves and the Chao estimate but how many sequences would we need to generate in order to capture a 16S from every organism present in an environment?