G.Fast and copper can only go so far. The future is clearly fiber.  The question is how long it takes to get there.  

Don't get me wrong, I love G.Fast and all the other near-magic tricks equipment manufacturers have pulled out of their hats to squeeze more bandwidth out of copper.  It's amazing you can get one gig or faster out of any short copper run between a household and a service node, much less "in place" wiring that has been in service over decades.  

Every five years or so, there's another improvement or two in copper wire speeds but the brutal truth is that each speed improvement comes with multiple catches/limitations.  Service distances shrink with speed increases, fiber needs to be pushed closer to the customer, distribution gear between fiber and copper plant needs to be deployed.

Copper is capable of delivering gigabit and multi-gigabit services with G.Fast, but it isn't clear that the economics over a decade or two are a net win over straight-line, all-the-way-to-the-home/business fiber.  And that's even before giving any credence to Verizon's claims that copper wiring is less "reliable" than fiber.

Contrast copper's speed increases with fiber.  Verizon started off offering 10 Mbps to 20 Mbps on FiOS and now is up to 500 Mbps.  Municipal fiber deployments, such as Chattanooga's, started out in the 100 Mbps range and now seem to be falling into a mean of 1 Gbps speeds while Google started at gig speeds that appeared to spur the latest round of gig fiber deployments by Century Link and Frontier along with cable DOCSIS deployments to support gig and multi-gig speeds.

Fiber deployments have been able to increase speeds faster, and it appears, with less overall hardware deployment and network complexity than a comparable high-speed copper deployment. Consider that Chattanooga and a few other municipalities are now offering 10 Gbps speeds to the home while Verizon has demonstrated 10 Gbps speeds on FiOS and hinted at the capability for up to 40 Gbps.  On the hardware side, ADTRAN and others are demonstrating fiber ONT hardware running from gig to multi-gig speeds.

Pulling fiber isn't easy or cheap, but if it isn’t deployed, there’s a "glass gap" left between service providers and customers.  Cable companies can get away with not fully deploying fiber to the home because they have a big coaxial cable in place for the last 100 to 500 feet to deliver service and most carriers aren't shy about replacing cable when needed.

An all-fiber deployment offers a clean sheet infrastructure unburdened by legacy hardware and the quirks of copper wiring.  While initial installation costs are bound to be higher due to all the digging and pulling, the upside of fiber is a much cleaner network capable of offering multiple-gigabit speeds with minimal hardware expenditures and a lot less legacy gear to maintain.  Deploying gigabit over copper is indeed possible, but leaving a glass gap between customer and the primary network will only result in more frequent incremental hardware expenditures and a "glass creep" forward to the customer as fiber is moved closer to support higher speeds.