This stuff is really, really basic, but: any interaction with technology or the products of tech companies must be exist within a context of informed consent. Something like #GoogleDuplex fails this test, _by design_. That's an unfixable flaw.
This is good to hear! But Google should have made consent an explicit part of the demo, then.
I think this is supposed to be the part of the announcement that alludes to possible consent? But... this doesn't communicate that, at all. ai.googleblog.com/2018/05/duplex… 
And if I put myself in the shoes of the product team, they probably thought, "Well, everybody gets robo-calls, and those don't require consent?" Which is a huge problem, but also the robo-call companies aren't doing as sophisticated data-mining of the targets of their calls.
