At the moment the miners for a block are awarded 12.5 BTC. Every 4 years this value will fall by half. For example, let's imagine that the prize value is 1.5 BTC for each block and that BTC's value against the dollar does not increase. In such a case, mining will not be very profitable.
At the same time, miners are also benefiting from the value of the fee. This time the fee values will increase. Then people will have to pay a high fee for bitcoin transfer. The biggest advantage of the Bitcoin system against banking systems was that they could shop without paying commissions to any brokerage house. If this happens, can bitcoin preference be reduced?
No really, only the BTC reward will be lowered but the BTC price will increase due to the law of supply and demand, less BTC less supply more demand, high prices.
Along with that fact we can also say that with the passage of time the remaining coins will reduce in umber and one day all of the coins will be mined and with the limited number of bitcoin its price will be much higher and the miners will rely on the fees of transaction which is also good in amount.