Stadia will have a presence on Gamescom Opening Night Live on August 19th. Along with other publishers and developers they will showcase World Premieres and announcements. This information comes to us through Geoff Keighleys twitter account.

https://twitter.com/geoffkeighley/status/1158741623200600064

There is also a Stadia Connect planned around Gamescom. Opening Night Live may have some extra news about Stadia.