I believe we will see a decline of the difficulty after halving day due to some big chinese companies shutting down and selling their equipment if the price rise doesn't at least compensate for loss of profitability. These super farms do not want to support the network but simply turn a profit. If the numbers are not rising, or are stagnating, let alone decreasing, some of them will liquidate their mining business.
Well, the difficulty has gone up to insanely high levels. Even if some larger miners shut down their mining operations, then the difficulty will still be very high. The difficulty almost doubled in the last 2 months and will continue to go up. Till now the largest mining farms have had enough time to earn back their invested hardware money. If the price doesn't go up as much as people are hoping for, then these farms can still make a profit.
Beside that, I really think the Chinese giant exchanges Huobi and OKCoin are up to something. If the price doesn't go up by itself, then they will offer a helping hand.