Yep. Soldered is just the best manufacturing process (besides on-package). Moving things close together simply delivers better outcomes and that will always trump openness concerns.
I would imagine that something like LPCAMM2 for GDDR is entirely possible and will never, ever be seen because people already accept replacing an entire $10000 GPU to get another 32GB VRAM on the next generation, so why give up that guaranteed revenue stream?