So cheap, all of cable will go DOCSIS 3.1. DOCSIS 3.1 is designed to do a gig up and down, but only the downstream is widely deployed. Gig downstream cable is deploying rapidly, with Comcast and Cox expecting to cover 50% of the U.S. in the next 24 months. Until now, cable upstream doesn't match fiber or G.fast, running 20-35 meg at best. Upstream DOCSIS 3.1 is not yet deployed anywhere, although Comcast has announced they will begin in 2017. Others will wait for full duplex.
Vodafone Spain is built around the former ONO, purchased by Voda in 2014 for €7.2 billion. It has 2.1M cable customers while passing 9.5M. The $50/customer cost is based on the $100M Huawei deal/2M; it also covers the homes who haven't connected, effectively lowering the cost. Note that the new modem is not included.
Early in the history of DOCSIS 3.0, Mike Fries of Liberty Global told the Times the upgrade cost was $20/home, even less than I had heard. (Plus new modem) The low cost made it easy to predict all the major cablecos would move quickly to 3.0. They did.