Phil Harrison: "The fundamental benefit of our cloud native infrastructure is that developers will be able to take advantage of hardware and power in ways never before possible. And that includes taking of advantage of the power of multiple GPUs at once."
This is supposed to be one of fundamental benefits of cloud computing, the ability to scale your compute resources as the task demands, so I don't see why this would be so surprising.
Yes, Stadia is capable of doing multi-GPU (really goes without saying/didn't ever need to be said). There is no indication of whether that would be a developers choice to target that, when that would be available, etc. and the launch instances of Stadia are going to be single-GPU.
This is supposed to be one of fundamental benefits of cloud computing, the ability to scale your compute resources as the task demands, so I don't see why this would be so surprising.
That's a fundamental aspect of hardware virtualization; neither Google nor Microsoft has said they are using GPU virtualization. The instances are dedicated hardware, not shared GPU compute.
Google saying that their tech is capable of stacking != "devs can choose to use multiple GPUs at launch."
It's very unlikely that they'll let a game decide how much hardware it needs.