they can and will keep providing access at a reasonable cost.. the average customer isn't gonna spend more that 150 on cable/internet combined.. and for the bandwidth issue they dont have to bury new fiber just gotta upgrade the equipment on each end of it.. that's the great part about fiber u dont have to replace it.
You realize that there is a TON of unused fiber in the ground that was put there over a decade by companies such as WilTel ( who now do not exist but their assets were sold to others). There's no need for more cross country lines, there's a need for much more last mile fiber lines.
There are research projects underway that may allow up to 99 more colors of laser light to be used in fiber optic systems. You could increase mainline data transport by 100 times today's capabilities. You have to build bigger laser facilities, but the bulk of the fiber strands already in place could handle the increased load. Very little digging may be required to do this, if it gets out of the R&D phase.