Anyone noticed that we have breached 17,800,000 BTC already? Which means that 85% of all BTC have been mined. And in the next 10+ years we can all assumed that 'almost' all bitcoin is mined already. Have you accumulated at least 1 BTC in your wallet?
Current bitcoin mined: 17,851,062 BTC
At the moment miners are rewarded with 12.5
BTC per block mined. In 2020 it will reduce to 6.25
BTC per block mined. There is a block reward halving every 4 years so if you do the maths the very last bitcoin will be mined in approx, the year 2140.
If the reward is reduced by half, then it's clear that the miner will start selling Bitcoin at a high price. The more difficult it is to be mined, the price will rise due to market demand. And I'm sure many people already know about this.