I can see the reasoning behind wanting to have confidence in system security, I expressed my view in another post, but maybe we need to look more closely at what the risks are in using Google's infrastructure, and other contributions such as Andrea Tatar's work in more detail.
If we are using the service to control security or mission critical processes, I agree that we need total control, but for general home automation maybe a balanced compromise is needed?
I've been trying @andrei-tatar's node for the past week or so, and I'm slowly seeing the potential being unfolded, especially as I've added 'Continuous Conversation' to my Home device (by switching to English (US) language).
You guy's know much more than me, what do you see as the main threats to such solutions?