I don't know enough about fiber to have a very intelligent discussion about it, but from what I've heard, one of the nice things about fiber is that you can run increasing amounts of bandwidth through the same fiber once it's laid as the endpoints improve.
I would expect that the buildout could be funded by a municipal bond issue, with the repayment being handled via the revenue from the customer-facing companies that lease access to the infrastructure. I've heard of municipal networks like this being run profitably and being repaid in a reasonable timeframe (on the order of a decade or two), but unfortunately I don't know more than that.
