Until you can play your Steam game library (and perhaps Epic and Unisoft and GOG) on Stadia, I think they'll struggle.

I have paid for Geforce Now which does let you play Steam et al games (although not everything is available which is annoying) - it is about £4 a month currently (or free if you can spend time waiting to play) and the experience feels largely the same to Stadia to me in terms of latency and quality. Many happy hours playing high-end PC games on a super cheap and lightweight Chromebook that starts up instantly and runs silently compared to my weighty, expensive, and noisy gaming laptop that needs to boot into windows (although that only takes 5-10s these days to be fair)

Feels like nVidia (...and Xbox? Not tried that) have eaten Google's own lunch in the stream-to-chromebook context.