For the relatively few people who upgrade RAM
Because let's face it that is a minority most of the time...
Directly exported PCIe lanes seem to offer a reasonable option - after all both Intel and AMD are already "sharing" the GPU memory when they can.
It will be slower than the on chip stuff, but it has ever been thus - consider it 16GB of cache, and then plug in "RAM" as needed. Could even take that memory between systems.
Biting the hand that feeds IT
