A bit wrong there.  Stadia already has multi GPU support in a master/slave configuration (up to 4 I believe), This won't be that efficient, but if they really wanted to play a numbers game, they already have that capability.  Again, I"m talking about advertising and public perception amongst consumers, not the real-world results.  They've also said that their hardware will be iterative as technology becomes available.
It will be interesting to see if Stadia shows any signs of life when the free version hits.  from what I've seen the games are just too overpriced, never mind the performance issues.