I'm not sure why you're assuming that a competing utility has to have separate lines. Here in New Zealand the power companies are not allowed to own lines - those are a highly regulated monopoly (The national grid is owned by the government, local grids by local lines companies.) Generating companies sell power wholesale via a trading system, Retailing companies buy the wholesale power (priced at grid-exit points) and deal with the consumer and local lines company. You can be a Generator and a Retailer, but not own transmission as well.
Interestingly the same model is being taken with the national fibre rollout - the fibre owning company will wholesale services to various ISPs and comms providers but will not be allowed to be an ISP itself. This avoids some of the effects you see where several providers build out fibre in the most populous areas, but you end up with monopolies covering less-dense areas and no-one covers the rural areas.