GPUs can still scale up by a LOT. The real limiting parameters are power consumption (which includes cooling), bus speed, production level of foundries. Think

GPUs can still scale up by a LOT. The real limiting parameters are power consumption (which includes cooling), bus speed, production level of foundries. Think super-[cross-fire/sli]. Economics will probably forbid that. This is a virtual limit which factors in the previous physical limits... in theory.