So just...put LPDDR on a DIMM? Or some other kind of removable slot?? I see no technical reason you couldn't.

Or, instead of soldering chips, make little LGA slots for the individual chips. I can't imagine the tiny added resistance from an extra millimeter of wire and pin surface contact would impact much of anything and even if it does, I'd rather take that than have no options when the next Windows update makes my machine a paperweight (obviously exaggerating, but it's getting there).