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?
Bitcoin is real invention of this century and also prepared with proper precautions. We must have to admire developer of Bitcoins because they have already predicted everything considering future of Bitcoin.
As we know after every 4 year Bitcoin halving occur. Which directly impact to price of reward after solving block. Bitcoin mining will be held till 2145. And I think Bitcoin mining will be there till mine last Bitcoin.
And till that time price of Bitcoin will be skyrocket.