What incentive is there for proof of work when all the bitcoins have been mined?

[GreenSky]

When all 21m bitcoins have been mined, what will be the incentive to run power hungry machines to keep the one true block chain alive and verifying transactions?

[Vladimir]

fees

[Nythain]

also, keeping the block chain alive and verifying transactions.
sort of an important thing to continue doing if anyone wants bitcoin to actually last beyond the minting period. there's a bit of a difference in perspective and opinion between those that view bitcoin as a viable digital currency alternative to the standard fiat currencies, and those that are just looking to get rich quick through mining and selling. hopefully, those that are in it beyond getting rich quick will stick around even when the getting rich isnt so quick anymore.

[ersi]

Do not forget that it will take years, to mint all of the 21 million full coins.

The idea is that the transaction fees is to be an incentive to keep working for the Bitcoin network, when the 'kick start incentive' is gone.

[Vladimir]

Block reward is simply a subsidy to miners to get the blockchain bootstrapped.