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.