Use ultra-dense routing of high isolation, low loss PolyStrata transmission lines to the ultimate advantage.  Add onto the architecture: antennas, interconnects, filters, time delay, MMICs, switches, inductors, capacitors, and a whole library of built-in passive components...compatible with standard assembly processes: BGA, solder attach, and wirebonding.  And another thing...each substrate-free metal backplane can be mechanically interlocked with another to form larger and more complex assemblies, with micron-level precision.