Much like FaceTime revolutionized video calling for Apple and iPhone users by making it easy for people to direct video call each other the new Google duo app will make it much easier for everyone else, including Apple and iPhone users as most Google apps work on all platforms and devices.
No, I do not feel that Google's Duo will revolutionize video calling. Firstly, there are already a number of similar apps in this area, Skype and WhatsApp, for example, which have a very large number of users. For Duo to take some of these apps market share it would have to show a much bigger difference from the already existing apps than it does. As far as I can see the only two selling points it has over them are: no need for a log in and stability (which remains to be seen).
We already have a lot of Video calling softwares and apps that serve the basic purpose of video calling. There are several option already available for different setups like individual video calling and group video calling or professional meeting video calling. I don't think there are any more ways to make it better.
Google Duo is nothing new, we already had Skype that was available for iOS and Android devices, we also have the native FaceTime for iOS, and many other apps/programs of the same sort. There is nothing special about Google Duo, as it is nothing that hasn't been done. Google is creating 'reboots' or 'remakes' of other great products that have already revolutionized the industry. They do it because they know that no matter what they make, whether good or not, people will buy it because of the cache associated with the brand name.