FIOS offers up to 50Mbps now in the US. Several Asian countries have had 50-100Mbps for years.
Even if you assume "everyone [and that's 1/3 the country] still on dial-up is such a late-adopter they're not even interested in HD yet", a lot of that broadband is less than 1 Mbps. And many broadband consumers have monthly bandwidth caps.
People with >1Mbps uncapped broadband is probably too small of a market to make purely digital distribution viable.
The latter part of your statement is true. They're not wiring up rural areas. However, I live in a neighborhood that doesn't have a home newer than 30 years and am receiving AT&T U-Verse, 20Mbps down (and consistent).
I don't believe the future is in shiny discs. The near-future probably isn't in exclusive streaming video, but the longer term likely is. We're a few technological break-thrus away, perhaps, but for what my opinion is worth... I believe it'll get there.