I used to work for our primary regional telco provider doing DSL and small business side networking.(was my first job and it drew me out of school lol)
The biggest limitation for DSL then was distance. The max distance was about 25,000 feet on the cable pair, that was for the lowest speeds, and if the wind blew too hard it could go out. lol You had to get within 15k feet for decent speeds(at that time), and within 5-10k feet for the best speeds.
For this new technology, it looks like even greater speed limitations are in place, which will make it a non-starter for rural areas. Their best bet would be to send their high speed out via some form of wireless, using repeaters. Really, it all comes down to how much money the provider is willing to invest.
The proverbial "last mile".