I know I'll sound like one of those 16Kb is enough kind of guys from the 80's. But seeing this number thrown around a lot, what exactly do we need 128GB of RAM for, especially in a console, even three or four years from today?
Surely our past issues with limited amounts of RAM were driven by the actual size of the applications being run on a platform. On PS1/PS2/PS3 the size of the games discs was at least an order of magnitude larger than the available RAM. Nowadays I can download a game that fits entirely in a PS4 RAM, and the largest ones are, at most, 5-8 times larger than the available RAM.
More RAM is always better, but only until we get to a point where the program running on it can fit comfortably. 128GB is at least three times the total size of some of the largest game out today, so unless our new consoles (and even new PCs) will be asked to run multiple games and applications at once, I don't see how loading them with unnecessary RAM would be an efficient way to budget for a new platform.
I don't see game size increasing much over the capacity of a Bluray disc, and seeing how we're all going digital more and more, size will be even more important. Not many people will want to download a 100/200GB game any time soon.