It seems to have taken off already :

> That's the case for many people these days–in fact, every week, over 10 million new people are signing up for Duo, and in many countries, call minutes have increased by more than ten-fold. https://www.blog.google/products/duo/4-new-google-duo-featur....

Disclaimer : Google employee but work far away from duo but use it daily with family and friends.