What happens when we dig the last bitcoin?

Currently, only trainers with the unique motivation to dig are getting the most reward (as Bitcoin) as possible, until the Bitcoin supply reaches its peak.
But, the day that the BTC was finally dug out, there would be no BTC to reward the digger. At that point of course the transactions will continue and should be confirmed to record on the blockchain blocks. So what do diggers do to confirm the transaction? That's the transaction fee.
The Bitcoin transaction is currently underway and is calculated based on the nature of each transaction. The higher the cost, the bigger the engine will be for a digger to validate it, so that it will be prioritized and implemented sooner.
This will become the driving force for excavators in the next century, once there is no BTC to reward. This was anticipated in the Bitcoin white paper by Satoshi Nakamoto:
"Once the amount of pre-determined currency has reached a fully circulated state, momentum can be completely transformed into transaction fees and become completely zero-inflation."