An interesting event we are all waiting for, even though it doesn't have a specific benefit for Bitcoin holders, but rather acts as a catalyst that triggers the price of Bitcoin due to scarcity over a period of halving cycle, which then leads to a bullish market. I think the last person to mine the last block would literally feel proud of himself/herself, knowing that their actions triggered what others have been anticipating.
With this slash in miner rewards, which would certainly lead to scarcity, I think Bitcoin miners and current holders would prefer to hold than to release, leading to the usage of more altcoins for side transactions. No one would want to trade their Bitcoin for things with less value, they would prefer to hold due to the increase in scarcity.