To me, it means that some miners could go offline. Not that the bitcoin network is going to shrink dramatically but it will most likely get smaller. It's going to be an interesting event. Many have speculated that after the arms race of ASICs started a bubble was caused and the loss of interest from traders resulted into miners actively reducing the price. Maybe we'll see a shift after the halving.

BTW this thread seems to be more fitting in the mining speculation board.