It all depends on software houses
Stadia's platform is already out there and available to any developer that wants to join the club!
It all depends on the companies yes. The ball is in there court. The stadia team has published many developer conferences and you can find some of them in the google developer channel on youtube. https://youtu.be/hMWjerCqRFA . Thats just an example.
Hi @Giovanniolvera,
Here is one of the recent announcements from the google team
Watch dogs and watch dogs 2 is one of the games listed