Lots of speculation about how long these apps will last. I personally suspect it's Hangouts that will be chopped. Google looked at Facebook Messenger and realised that the future was in personal assistants and the illusion of virtual/simulated AI, and realised also that Hangouts would become an unmanageable mess with more features added, so they are rolling out a Messenger competitor and a Hangouts video replacement with a transitional period to assess both feasibility, interest and to enable Hangouts customers to explore alternatives ahead of the shutdown, while attracting new business along the way.

Personally, I like Duo because I can talk to my partner with video even though my partner is on Android and is a bit of a technophobe.

The almost-too-simple UI is much easier for my partner to use than Hangouts, and Skype is a dog. I also do not use Facebook.

Google, like Apple now, and like Microsoft before it, is playing catch-up to Facebook and arguably has been since Google+. It's like Hollywood: remakes are far from innovative and are loathed by many who liked the originals or who crave fresh material, but a remake is much easier to get through the boardroom and easier to make profitable. Google should be pushing the boundaries but it's afraid of tarnishing its credibility with potentially bad decisions. They also want to appear active I suppose, and to collect what data they can from people who are likely to be loyal to a Google competitor to Facebook.

I think Google should be thinking doing more than buying up tech talent in acquihires and inflating an already bloated app ecosystem that threatens what business they already have, but I'm not a business person.