Would it be that Sony has got the CPY soldered in there n the first place. Laptops are still too proprietary.
Well.. I think most laptops are going to be socketed rather then soldered.
Simply because it would be easier to repair, if the CPU is dead, or if the customer wants a faster processor (different package as far as cost).
I really haven't seen a soldered CPU before for laptop.
Though I agree there isn't going to be many choices as an upgrade path, especially because of the chipset and bios settings.