That's the thing, who is everyone? Such technology would only be relevant to premium-level ultraportable notebooks. Desktops, gaming laptops as well as budget laptops would stick with the cheaper and more ubiquitous DDR. Smartphones and tables will continue to solder RAM on due to space constraints. Apple (who is the driving force in this market segment) won't be interested since they are going fully custom and I doubt that an LGA socket will work with their on-package custom-build wide RAM interfaces. So in the end we are left with things like Dell XPS 13, MS Surface and few others. These are all popular and impactful brands, but they are just a drop in the bucket compared to the total PC sales. And I doubt that technology reserved to only selected premium laptops is going to be cheap.
If LPDDR is faster won’t desktops and gaming laptops also want it?
One possible other compromise could be soldered LPDDR RAM, but with a DIMM expansion slot for DDR as well. I wonder whether the DDR could be switched off and the baseline power draw eliminated if the RAM usage was below needing it.
So I will preface this with that I'm not an expert. But as I understand it, multicore systems are already frequently NUMA, but to a degree that most stuff (I am eliding categories of code here, but you get the idea) don't have to really care. From my understanding of how all this works, the difference of speed and bandwidth for LPDDR versus DDR seems like risking significant complexity for an expandability that few people would use and in turn cause an everything-or-nothing problem, where either high-performance code is written assuming anybody might have this, or nobody assumes it and you get a pile of stalls.
