I don't see this as affecting the value in that way. It's not an overall supply issue. Most bitcoin is not in circulation - it's mined and held. That's not going to change; if you're selling to cover your operating cost, you're going to continue to do that at the same rate. If the value goes up, you will need to sell less coin to cover the same cost.
However, the truly critical variable is hashrate. All of the hardware out there is reflected in the marketplace as hash rate, and (for the most part) is governed by the rules of economics. There is sunk cost that needs to be recovered, and that hashrate will be applied in the most profitable way (again, generally - there will be people who run "unprofitable" rigs and bet on the exchange rate increasing). After the halving, what will happen to the difficulty of SHA256 altcoins? Will hashrate move to those coins and re-level the profitability and difficulty across all coins?
The hardware situation is also interesting. A few years ago, you had choices for your hardware purchase. Now you don't. At this point, there is bitmain and other Chinese industry that has exclusive control over the hardware supply and access to state-subsidized energy. At the current hardware price, exchange rate, and "western" electricity prices ($.10/kwh), an S9 WILL NEVER PAY FOR ITSELF. It certainly looks like we're a bunch of suckers.
The other thing I'd like to know is what happened on 25 May. It's like the exchange rate went cuckoo all at once.
Miners are going to keep mining, everyone will keep doing what they've been doing, aside from the value going up so the miners can compensate for the smaller supply. A halving of the supply doesn't mean that everyone has to shut down, it just means they sell their Bitcoin for more.
It's like how gold is mined, because there is less available in the ground not everyone doesn't mean everyone shuts down, it means they sell it for more, to cover their costs.
I do not quite agree, you see when the rate at which btc is mined reduces, it's true that demand will still remain high and more miners will open their 'treasure house' and sell. This is exactly what will bring the price down, so many people selling btc will make the price drop...