Ready for customers 2019-2021. John Chapman made cable engineering history with the first demonstration of full duplex cable at ANGA COM in Cologne, pictured. The setup doesn't look like much until you realize this is the world's first prototype of a 10 gigabit down, 5 gigabit up, cable system. By using the same spectrum upstream and down, remarkable speeds are possible.
Chapman outlined the path to gigabit cable in 2005. Almost no one believed it possible except for a handful of innovative engineers. His ideas became central to DOCSIS 3.0 and 3.1. Comcast today is offering the gig downstream to millions of customers. If John says FDX gigabit upstream will work, I'm a true believer. (The schedule isn't guaranteed, of course.)
Full duplex communication has a long history, but not at the speeds of today's wireless and modems. Phil Levis & Sachin Katti of Stanford have spun off Kumu Networks, which has ambitious plans for wireless FDX and inspired renewed interest.
FDX for cable is a harder problem. Cable systems are "point to multipoint" - one central unit, the CMTS, attaches to many homes. The challenge with point to multipoint is that an echo canceller can only be used at the CMTS end.