Right now, Google voice services are fragmented. You have developer tools on one side and Google Assistant on the other. In the middle, there’s Google Now, Google Voice Actions, Android Voice Typing, etc.
Google Assistant is baked into the Pixel and Home devices. However, on Android and Apple iOS, it comes as a contact on Google Allo. I’m sure Allo is ingeniously built but it’s difficult to get people to migrate away from their existing messaging apps. It’s an investment to learn a new app for SMS and inevitably, it’s less powerful or stable than the native app.
Google would be wise to quickly release Assistant to all hardware as a replacement for Google Now (or widget… whatever they’re calling it) and the Search app. This would help entrench them ahead of whatever Samsung might release at Mobile World Congress in two weeks.