Google has launched its Assistant on the iPhone, replacing previous voice assistants it has made available to Apple's customers.
It's a futile effort to persuade users to abandon Siri in the long term and clearly demonstrates how Apple is going to win not just the smartphone war, but probably the whole of consumer computing.
The problem with Google Assistant is that you can only use it on the iPhone by launching an app. Siri responds to a voice command reducing friction and significantly impacting the appeal of Google's tool.
The smartphone is your most personal and most used device, the voice assistant you use elsewhere will be defined by which phone you use. As voice assistants become more popular this will be an even stronger draw.
So the fact that you own an iPhone leads you to an iPad, then an Apple TV and eventually the new Apple home assistant, because your voice assistant becomes infinitely more useful if it's ubiquitous.
If you agree that the smartphone market tends towards iPhone over time it isn't a great leap to say that Siri drives the rest of consumer technology towards Apple as well.
Right now Siri doesn't have to be very good, it just has to be good enough to keep Apple users interested.
And Google, Amazon and Microsoft can make their assistants as powerful as they like, but without access to the iPhone's market, ultimately they aren't going to get anywhere.