There is no way that bitcoin will end with just a decrease in mining profit. It will continue but the confirmation will take a very long time. The users will pay huge fee just to get the transaction done in time. But let us say a miner will stop mining because it is no longer profitable what will happen next, a new miner with a good hardware will replace the old miner and the cycle will continue. New mining hardware, new technology will just come out to solve the problem on difficulty, electricity and others.
One of the biggest problems of Bitcoin is the time to approve payments. At the moment we can say that your payment will be approved in 0-30 minutes with a minimum value of 90 satoshis/byte. For the average transaction size of 226 bytes, you need to pay 20340 satoshi. Average fee values can be viewed on this site
https://bitcoinfees.21.coBitcoin was the first time the fee values were very low. Over time, these fee values increased. One of the reasons people choose bitcoin is that the commission fees are low in transferring money.
If the block award value is 1.5 BTC in the future and the bitcoin price does not increase, this time the fee values will increase so that the miners can make money. If these fee values are more than the money transfer fees of the banks, there is a possibility that people will drop the bitcoin.