Right now we're approaching about 17 million out of 21 million possible bitcoins. When we reach the max supply, what incentive would miners have to continue mining and verifying transactions? Sure they can still collect fees, but why not mine newer and more profitable coins where they have the chance to collect both fees and new coins?
What's stopping the entire blockchain from grinding to a halt, prohibiting users from conducting transactions, and thereby making bitcoin worthless?
I think when all the bitcoins have been mined, the price will spike higher. Maybe triple the price once the last bitcoin has been mined. I guess all miners would shift to other coins after mining all the bitcoins. I think most miners must've already made a plan to start mining alt coins after bitcoins.