Dark blue: Firm commitments from incumbent: BT (10M), Belgacom, Australian NBN, Swisscom, Austria, Bezeq Israel, Chunghwa Taiwan, Telus Canada, Telekom South Africa, SK Korea, (U.S.) AT&T, Century, Frontier, Windstream, Belgium, Omantel
Light blue: Smaller carriers in Germany, Norway, Finland, Japan
Many carriers prefer G.fast in buildings where full fiber is expensive to run. AT&T has been very unclear which of their 12M+ planned homes would get fiber to the basement/G.fast and which would get fiber all the way. They've brought fiber to a million commercial locations and I believe more than 10,000 cell sites. It's relatively inexpensive to extend some of that to residences, well under $1,000/home. (The quotes from Bill Smith are from an excellent Alan Breznick interview. Smith, then CTO of BellSouth, led the recovery after Katrina. He's always worth listening to.)
By late 2014, competitors saw AT&T begin a massive "fiber" build in apartment buildings, complementary to their commercial fiber. AT&T engineers played a major role in defining G.fast. The standard was written to the needs of AT&T and British Telecom.
Better cable doubles reach. Calix used a 16 port fiber-fed distribution point to deliver 500+ megabits 2,000 feet. For many years, American builders have wired homes with coax, most of which are served by the local cable provider. But 8% of the U.S. does not get cable broadband. If coax is in place, Calix has just demonstrated an alternative.
In addition, some developers prefer to maintain exclusive control of broadband. G.fast over coax could be a tool for a non-cable company to compete for the business. Within a building, there's a pretty stark performance difference between G.fast and VDSL.
If you have fiber to the basement, anything but G.fast is obsolete by the end of 2016 and possibly sooner. BT is proving G.fast works in the field
Inspired by strong customer desire. The original G.fast plan for 8-16 ports isn't nearly enough now. BT and others have decided to use far fewer terminals, each with more lines. Vectoring 48 or 96 lines is not a trivial problem. Imagine the calculations for so many lines running at 500 megabits over 106 MHz. The heat alone is a problem for small field terminals. It will require at minimum semi-custom chips optimized for the application.
Huawei is confident that "long reach" G.fast will soon see improved performance. Confirming the early field trials at BT, they expect it will be practical to increase the power used by a few dBm. My cable friends are working on 2 gigabit systems, possibly using full duplex technology.
Sckipio suggested last year they were close to vectoring 48 lines using dedicated processors. Now, Huawei's Jack Zhu tells me they have a 96 port unit on the roadmap for Q4 of this year, based on Broadcom chips.