When supply drops, and demand stay the same, prices will rise, that is what will happen if Halving. We know that the current block reward is 12.5 BTC being minted every 10 minutes and after halving only 6.25 BTC will be minted every 10 minutes.That means that there will be fewer coins being sold by the miners.
This will lead to miners to decide between two possible options, to sell their BTC reward for a higher profitable price, or to remain with the price but continues to mine but will surely lead to them to realize that their profit wasn't enough to pay for the electricity bills they have and might turn out to them selling their mining facilities and leaving the market.
Any two could happen but what surely does is expected, is to see the people in cryptocurrency space like us to lead the market in higher price considering the positive option that miners could choose.