I wonder about how strong the consumer demand for gigabit internet actually is. If you're reading this, you probably have it or want it if you don't, but if you're the average person looking for a place to live (rent or own), how much will available internet speed be a factor (compared to location, cost, and other considerations like schools, fire stations, nightlife, commuting distances, access to public transit, and so on)? A family of 4 can all stream different HD content on Netflix with a 25mbps connection. Not many homes would have multiple 4K/UHD displays, so would likely be ok with 50-60mbps. What else are people needing all this bandwidth right now?
ISPs are holding out though, when Google came into town the current monopoly "magically" came up with 3X speeds. (300mb/s). Seemingly out of nowhere.
Lots of factors, but $ is probably the largest
In rural western Utah (and eastern Nevada) we get fiber-to-house from a relatively small broadband company. It's pricey, and they are literally the only available service (apart from satellite), but they are doing great work. A few years ago, I thought the best this <50 house town could ever hope for was DSL. I was happily proved wrong.
My hope is that there are more businesses willing to do the same thing across the US.
As long as they can ride an old cash cow un-challenged theres not much incentive to spend money to innovate their already dominated markets.
Also I'm not sure if GPON deployments can really be considered as "gigabit" given the shared medium, 5G fixed wireless even less so. Gigabit DOCSIS does look possible (but using more spectrum per user,) I don't think there will be a massive push for it either.