The useful life of fiber installs can be even shorter than 10 years in specific cases [1].
What if the municipality owned, laid, and maintained the physical conduit/poles/enclosures but not the actual network physical plant itself, which is then deliberately designed to be replaceable so commercial providers fish through the cabling they want to municipally-owned physical hubs that are equipped and operated by the providers? The municipalities already have the resources and staff to do so relatively competently from water, wastewater and electrical grid deployment and maintenance. Most of the cost of last-mile deployment is the physical laying, but if that is shifted to a public utility while fishing cables (at most) is left to the providers, then might the providers see dramatic increased incentives to compete on quality of service and price?
Except you almost never want to pull fiber when you can help it (fiber is far more fragile than copper). In the scenario you describe, instead of burying a conduit, you would just bury a jacketed fiber bundle containing hundreds of fiber threads, even if you only need a couple dozen right now. This is where the term "dark fiber" comes from. Also, in this scenario, if a fiber cable "goes bad", you can just swap out another, unused cable.
Regardless, the architecture you propose would be incredibly expensive for ISPs to implement on any large scale - so much so that it would create significant barriers to entry for any new entrant, and a big incentive for horizontal consolidation. Ideally, the utility ISP would provide route tunneling from a specific port on their demarc switch representing a home to a specific provider at a NOC at the edge of their network. This does create some bottlenecks, but it's better than having 5 ISPs have to put 1,000 switches all over a city just to cover all the homes. Coverage is the entire problem that causes a monopolistic situation - so let the shared service provider worry about coverage.
Even still, I'm not sure of the value that ISPs provide in such a scenario. It seems like a commoditized service with very little in the way of competitive advantage - which means that advertising dollars will be the biggest differentiator (similar to how it is today).
Good points, thanks for contributing your domain knowledge. So the issue seems to remain: fiber can be made in different ways to accommodate different signaling technologies, and what we lay down into the ground and run through buildings today might not be what we want to use 5/10/15 years from now. Is there a potential way to economically mitigate that, and at the same time turn Internet access into a public utility so the bulk of the initial capital costs are somehow only paid once by the utility?
When you are dealing with a city of millions does it really seem right to fish one wire at a time? That means terminating the wire at the home too. With multiple ISP's how many of them would need access to the "Main St" section at a time? The cost of booking a time, sending a worker out to fish and terminate possibly kilometers of wire per customer as each customer signs up would be a logistical nightmare. Then what happens when the customer leaves you for the other guy? Never mind the cost differential of running one wire vs bundle of wire.
What if the municipality owned, laid, and maintained the physical conduit/poles/enclosures but not the actual network physical plant itself, which is then deliberately designed to be replaceable so commercial providers fish through the cabling they want to municipally-owned physical hubs that are equipped and operated by the providers? The municipalities already have the resources and staff to do so relatively competently from water, wastewater and electrical grid deployment and maintenance. Most of the cost of last-mile deployment is the physical laying, but if that is shifted to a public utility while fishing cables (at most) is left to the providers, then might the providers see dramatic increased incentives to compete on quality of service and price?
[1] http://www.quora.com/What-is-the-lifespan-of-fiber-optic-cab...