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 all the bitcoins available would have been mined and then there would be nothing left to mine, so all we can just do is to keep confirming transactions as miners then, and earn just a little from transaction fees.