alt Hacker NewsYes. Signal integrity is so finicky at frequencies DRAM operates that whether you drill the plated holes on boards that complete the circuit to go completely through the board or stop it halfway starts to matter due to signals permeating into the stubs of the holes and reflecting back into the trace causing interference. Adding a connector between RAM and CPU is like extending that long pole in the tent in the middle by inserting a stack of elephant into what is already shaped like an engine crankshaft found in a crashed wreck of a car.
Besides, no one strictly need mid-life upgradable RAMs. You're just wanting to be able to upgrade RAM later after purchase because it's cheaper upfront and also because it leaves less room for supply side for price gouging. Those aren't technical reasons you can't option a 2TB RAM on purchase and be done for 10 years.
In the past, at least, RAM upgrades weren't just about filling in the slots you couldn't afford to fill on day one. RAM modules also got denser and faster over time too. This meant you could add more and better RAM to your system after waiting a couple years than it was even physically possible to install upfront.
Part of the reason I have doubts about the physical necessity here is because PCI Express (x16) is roughly keeping up with GDDR in terms of bandwidth. Of course they are not completely apples-to-apples comparable, but it proves at least that it's possible to have a high-bandwidth unsoldered interface. I will admit though that what I can find indicates that signal integrity is the biggest issue each new generation of PCIe has to overcome.
It's possible that the best solution for discrete PC components will be to move what we today call RAM onto the CPU package (which is also very likely to become a CPU+GPU package) and then keep PCIe x16 around to provide another tier of fast but upgradeable storage.