It's not (only) that 1Gbps to the home, it also that fat pipe per street, the even fatter pipe per neighborhood, etc.
Especially the latter pipes need to get a lot fatter, the more people use that 1Gbps bandwidth.
Look at it this way: roads to houses haven't increased in bandwidth in the past century or so, but investments in highways have. Why? People started using 'their' bandwidth. They don't walk to work, but use a car that takes more room, and also travel over larger distances.
Funny story about that 1gbps needing fiber. In fact, a DOCSIS 3.1 modem at 24x8 will easily hit 1-1.5gbps with half the investment necessary as it would to roll out today under DOCSIS 3.0. So expect to magically see cable start competing with Google Fiber if it actually takes off! ;-)
Now, admittedly wiring up all the suburbs and rural areas might cost more, but the incumbent players are really not so beleaguered [http://finance.yahoo.com/q/is?s=CMCSA+Income+Statement&annua...].