Standard memory modules which were soldered onto the mainboard? Given how Macbooks have had soldered memory packages for ... 8 years now, I don't think moving

Standard memory modules which were soldered onto the mainboard? Given how Macbooks have had soldered memory packages for ... 8 years now, I don't think moving the memory onto the SoC was to lock out upgrade potential. It doesn't make upgrading any less possible than "completely impossible", and probably (slightly) reduces the overall cost/complexity of the board, slightly reducing the material cost/impact. FWIW, in the future I imagine most processors will look like the M1, with additional memory available over a serial bus like OMI, used in POWER10. The "unified memory" will effectively serve as a giant cache for the CPU/GPU with slower peripheral memory used as a backing store.