Stadia is potentially the very best streaming platform out there. Better than xCloud and better than GeforceNOW. However, there have been a few missteps that make it difficult to continue in the current fashion because everything is about content.
1: Google wants everything completely in-house and offers unusable developer tools that make converting games simply time-consuming and relatively expensive. Absolutely no connection to existing libraries such as Steam or whatever, so that the end user also has to purchase everything separately as if it were a console.
2: The promised hardware performance is not delivered. Since day 1, major concessions have to be made for 4K and because Google uses its own custom stuff, it is difficult to optimize to get the best out of it. Result: Modern games on low/medium settings and 30FPS. Too bad, since the server approach should in theory be very scalable.
3: No HW upgrades have been made yet. Where you can play with GeforceNOW at 3080 level without concessions, Stadia remains in a kind of Xbox One era.
If Stadia is serious about getting involved, they should make very good arrangements with eg Steam, major game studios or even manufacturers such as Sony and Nintendo. I don’t think they can get in the way though, because everyone wants to get the most out of the profit margin. You now also see that Nvidia is running into the problem that game studios give an opt-out for GeforceNOW, while the end user brings their own game licenses. Nvidia offers nothing but a kind of virtual PC. The fact that a vague legal clause can be claimed at all is super unusable and shows that the market is completely boarded up at the moment.