In a tweet today Karim Jovian has said he will be demoing Crowd Play this Monday. With this tweet we do not know what game will be getting demoed but there are a couple which we know do have Crowd Play coming. Dead by Daylight, Get Packed, Bomberman and Embr have all touted the feature.
Update we have received comment from Stadia
We’re currently testing the ability to live stream Stadia games with a small number of testers. Stay tuned for more information. Here’s more info about experiments on YouTube: https://goo.gl/TD4ZD5
Update 2 The game being used for Crowd Play is Mortal Kombat
Update 3 Crowd Play will be demoed on the channel below.