It cannot happen because there is a protocol being enforced by the full nodes as part of the decentralized network and in that protocol the block subsidy is clearly defined and it cannot suddenly "stop" without performing a hard fork to change the protocol first. And that's not happening either.
Technically, Bitcoin can't suddenly lose its mining reward without a major protocol change. The block subsidy is embedded in the Bitcoin consensus itself: it decreases by 50% every 210,000 blocks (halving) until it reaches near zero in 2140. You can find the reference here:
https://en.bitcoin.it/wiki/Controlled_supply?utm_ This rule is also fully enforced by fullnodes. When a miner creates a block with a different reward, the network automatically rejects it.
Furthermore, in a thread created by Satoshi, who initially designed this incentive to gradually shift from block subsidies to transaction fees, you can also see it here from @satoshi .
Right. Otherwise we couldn't have a finite limit of 21 million coins, because there would always need to be some minimum reward for generating. In a few decades when the reward gets too small, the transaction fee will become the main compensation for nodes. I'm sure that in 20 years there will either be very large transaction volume or no volume.
This is why the Bitcoin consensus is so conservative, making a hard fork to change the reward type virtually impossible.