This morning I was talking about this with a buddy of mine.
Right now we have miners all over the world trying to solve this exponentially hard algorithm to earn their bitcoins. That is their incentive and that is what drives them to do so.
What happens when we remove that incentive to "mine" aka "verify transactions" on the blockchain? What I'm basically asking is what happens when we hit 21,000,000 bitcoins from the perspective of the miners?
Then there are no more block rewards for the miners. Regardless even if the last block of Bitcoin is already mined, miners will continue to mine for the purpose of processing Bitcoin transactions. So if we are going to look in the aspect of profitability, then miners will only rely on transaction fees. We won't be seeing this, it will happen after more than a hundred years from now (I do not know the exact digits

). That is if Bitcoin will still exist on that point, though.