it won't be long before only the most low-end system would stand for a socketed CPU on a mother board,
Actually, the most low-end system I know is The Raspberry Pi, at $35 with 512MB memory, USB and Ethernet. It uses a soldered Ball Grid Array CPU with the memory stacked and soldered on top of it. Only the Ethernet/USB hub is on a separate chip. The whole thing is the size of a credit card, except for connectors sticking out here and there.