The halving may result in less block reward, but it does not result in less SHA mining equipment. Mining pools may draw back hash power temporarily, but ultimately the miner needs to be compensated for the energy expended. This means, after the supply shock of the halving, the new minimum price will be at least double of what it was before the halving. All else being equal (in particular, demand and available hashpower being equal) this means the cost to produce the same amount of bitcoin doubles. This says nothing of the speculative-demand, value-store demand, and use-demand driven components of future prices.