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?
I think they are balance the profit and fees for those who are mining bitcoin.. and i think it will not end bitcoin because of the block rewards are decreases every 4 years or block halving.. the price of bitcoin is always depends in the supply and demand so if our block rewards are decrease i am sure that the price could be rise that can increase your profit or it can be still balance because of the price increases.
Its impossible that the price will not increase and mining will not profitable. if the difficulty is increased i think your mine coins daily will be deacreses but the price bitcoin could be increase because bitcoin is in demand and many companies right now are using it. .
I also think that bitcoin mining profitability have the capability to balance itself. As long as there is demand for bitcoin, mining will always be profitable at the end after all the adjustment of difficulty. It was just now I realized how great is the design of bitcoin ecosystem.