Are you familiar with Bitmessage? The mining incentive can just as easily be usage of service provided by the network which uses the given blockchain. Even if

Are you familiar with Bitmessage? The mining incentive can just as easily be usage of service provided by the network which uses the given blockchain. Even if the miners weren't interested in consuming the provided services on their own, the network could rely on miners being rewarded with services which they then sell access to.