I think that in order to properly estimate the expected price after Halving should look at the schedule difficulty and hash rate. If the miners begin to massively roll up, the price will be able to stay at less than double the price in April-May, that is, less than $ 800 dollars. Otherwise, ie if the miners would have enough patience (and stocks) not to sell Bitcoins cheaper and continue to main unabated, a new stable level will be somewhere between $ 800 and $ 1,000