Good discussion that brings some clarity to the issue. Another way of organising our systems that fits into the bottom right hand corner of logically, politically and architecturally decentralised are “Complex Adaptive Systems” (CAS). The political decentralisation is most important as it provides the reason why we bother building these systems. When we make loans a CAS distributes control over loans to lenders and borrowers and removes the cost of compliance embodied in centralised systems. The cost of money compliance is interest on money and removing it with a CAS halves the cost of most infrastructure investment projects.
Any IT project involving communications between autonomous entities can be tackled with a CAS. All the cases I have examined bring substantial savings and increased functionality if turned into a CAS.
Another way of thinking about a CAS is that it is a pre-frontal cortex for centralised systems.