I wonder if there is any use of this for the home assistant community 
like enable access to features that previously was hard to get to work.
It would appear so:
This means that any app maker — smart home-related or not — can access the over 600 million devices connected to Google Home
Previously it was only the other way around, Google Home could access HA devices.
I hope that this will provide access to devices that can be controlled by Google Home, but doesn’t have integration with HA
That is exactly what this means.
A huge data grab by the master of grabbing data.
Opens up before killing it as bunches of other services in the past, always keep away of Google and other big tech companies for technology 
Lets hope they open up their own devices a bit more also at the same time.
So that we can get sensors on speakers that is currently not possible
I hope we get better access to trigger routines. Google is light years behind in automatons it feels like, but they do expose a few really nice actions. I particularly like their news feature.