Blockchain PoCs are useless
Proof of concept is a realization of a certain method or idea to demonstrate its feasibility, or a demonstration in principle, whose purpose is to verify that some concept or theory has the potential of being used. A proof of concept is usually small and may or may not be complete.
Blockchains -the immutable, tamper-proof and transparent records of events- are most valuable in highly regulated environments as I wrote earlier. Therefore building a Proof of Concept might be an interesting exercise for developers -and a lucrative business for some- it is useless as it does not proof anything since it will not be live in a real environment. And that real environment is the place where blockchains proof their real value. And I am not talking about whether customers will buy and against which price and in which color; in the real world your blockchain solution meets real legacy IT systems, legacy regulatory frameworks, legacy networks and legacy strategies. Only than you will have real Proof of your Concept.