Google refers to Allo as a smart messaging app, created to "help you get more done in your chats and express yourself more easily". The service is shutting down in March 2019, giving people time to export their conversation histories.
The shutdown has been expected for some time. "It's one of Google's highest rated mobile apps and is seeing strong growth and engagement across both Android and iOS". It does seem that Hangouts is being focused more on team collaboration rather than normal chat, and Messages may take over the latter objective. For a "smart" messaging app, that problem alone is enough for it to lose users. Allo will continue to function until the end of March 2019. The company's also continuing to develop Hangouts into a workplace collaboration app, helping it to rival the likes of Slack.
In a post on its official blog, Google laid out a simplified messaging strategy for the future. And after that it will be gone.
The blog post also mentions that Hangouts Meet and Chat will eventually become available to all users, and the company is "fully committed to supporting Hangouts users in the meantime". For team-based messaging and enterprise users, Hangouts Chat and Hangouts Meet will take care of chat and video conferencing scenarios.
Google didn't dispute this in any of their clarifications, only acknowledging that they'll soon offer Hangouts users the chance to use Hangouts Chat, which is now only available to G Suite customers as more of a collaboration tool.
Meanwhile, Google will focus on Messages.
Today's announcement does a certain amount to change all that, but still leaves Messaging, Duo and Hangouts doing more or less the same job in a different way. The company has shifted focus to Messages for texting, Duo for video calls, and Hangouts Chat and Meet for G Suite customers.