Developing a game that runs on Stadia and one that runs on the customer's local Linux box are probably going to be two different things, unfortunately. :-(
Much like web apps, YouTube, Netflix etc. today already work flawlessly on Linux, so will gaming too with this development. For most people, the browser is already the only "native" desktop application they use on their computers.
Web apps and web video finally made the Linux desktop viable, but also irrelevant in the bigger picture.