Thank you to Lena for pointing this out to us but it looks like Stadia will be expanding to Australia and Japan very soon. In a YouTube video on the official Google account to be considered to be part of the makers program you need to be part of countries supported by Stadia development. If you check out the video below both Japan and Australia both feature allow those countries are not yet supported.
Japan and Australia are highlighted in a different colour to indicate that Stadia is not available on the country. This would however lead us to think that Stadia support should not be too far of if developers are able to access the services.
Could this be a surprise for the coming days ahead? Time will tell. What do you think? Will we see Stadia in other countries soon?