I imagine we can have SOC of CPU+RAM in one package and save on their wiring, for example.

Typically you'll use PoP with modern SoCs, where you put the memory on top of the CPU so connections don't go through the PCB

Place FPGA blobs down, now you have hardware like software components. But not an option for battery powered products, because of the high power requirements of FPGA's.

Not only that, FPGAs can't do sensing, can't condition analog signals, can't drive large currents. The power consumption is just one of many limitations.

FPGAs could be one way of moving things into "software". IMO we need a revolution in "programmable" hardware before open hardware can really take off.