It's probably more than 100 years from now.
Let's remember it's 21 million coins.
Each certain number of blocks the difficulty increases, because the number of coins that are delivered with the mining of each block in the chain is reduced. Bitcoin established that every 210,000 blocks would reduce the reward for each mined block by 50%. So every time the part that touches us is smaller. Today the reward is at 12.5BTC for each new block verified.
The next reward reduction, according to BitcoinBlockHalf.com, will happen in May 2020 and will be reduced to 6.25BTC. That is why even if 17 million minutes are already mined, the duration will be extended.
Nakamoto already thought about this and established that the nodes were responsible for maintaining the blockchain and verifying the transaction. This would move from a current proof-of-work (PoW) trust system to a consensus test system (PoS).
When the last Bitcoin is mined, miners will already only receive rewards for the transaction i.e. commission. Already Transactions by then with Lighting Network fully integrated will increase, but there could also be a commission war and these increase.
What do you think?