There was a piece in the print edition of the Times the other day that said BT (OR) were planning to have packages offering Broadband only services, something which I think I've read about on here a while ago.
What was interesting was that the article also said that BT were planning to deliver voice services via Broadband (VoIP) and cease the old style telephone service by around 2025, something which I'd not heard before. Given the minimum call cost is going to be around 30p for a 1 minute call, I can see it hastening the arrival of domestic VoIP for those with decent connections and/or dodgy mobile services.
Presumably rural and remote communities would still be able to have old style telephone services unless the idea of a Broadband USO became a reality. Even then it would need to be as reliable as POTS, something I doubt would be achievable for a while yet.