The argument by specialists, the few that are left, has long been that without a human being intervening to keep trades orderly, there will be an uptick in volatility. The argument has been raised anew. Joe Saluzzi, of agency broker Themis Trading, has argued as much, saying all the volume is going to screens. The advent of Reg NMS, which became active on March 7, is fueling all this to a greater extent. Saluzzi estimates that the share of trading conducted via humans has fallen by up to a third in the past two months. So the issue really is how to ultimately wind down the floor. One could just throw up a "would the last specialist please turn out the lights" sign. But a more orderly approach will be required. How does the floor finally end. Or does the NYSE keep it for tourism-related reasons? I'm not sure.  

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- here's the article from Financial News Online