The block reward will seize to exist at some point in time.
What could be used as a further incentive to mine?
i don't think the block reward ever seizes to exist, because the reward only "Halves" every fixed number of blocks. and also there always will be the transaction fees included, which is received by miners. and if the price rises that little amount will be worth receiving
IT will seize to exist at some point , when all the 21 mil coins will be mined ,the blocks will give no reward but they will be empty and will be used for confirmation , the miners will earn through the transaction fees that will be paid , so may be the transaction fee will increase or maybe not if the price takes a jump , and it sure will , seeing how much time we have