I agree with you that rural-broadbandification will be as important as rural-electrification was in the '30s. That said, I think that most lucrative (read: capital efficient) business model here is low-bandwidth web sites, not high-bandwidth ISPs. Does a news site really need to ship 2Mb of JS, a 20Mb auto-play video, and 5Mb of ads to communicate 1.5Kb of plain-text? Maybe if your users have fast connections but not if they're in rural Idaho and it takes 2 minutes (that's 2,000 milliseconds) to load a single page.

Edit: numbers