FIOS and its kin will be maintained where they exist already, a pathetic fraction of the country, but not expanded.
Well, frankly, yes. Verizon has said for several years that the cost of rolling out FTTH for FiOS was so high, and the adoption rate low enough, that they are done with expanding it for the foreseeable future. Verizon is a business, and FiOS just isn't making much profit. And that is with Verizon having no obligation to share its fiber with other providers, unlike the copper TDM network sharing requirements for UNE-P and DSL. If Verizon had to treat FiOS like a utility and/or line share, it would have been deployed in even fewer places or not at all. It sucks, but it's true.
To be treated as a utility generally means to be compensated in a "cost-plus" environment. You are allowed to charge consumers what it costs you, plus a little margin. Fair enough for water and electric, say, but those are industries where the infrastructure was built a long time ago and a need to upgrade customer-facing physical plant is not really an issue. Bu if you want to build a new power plant, or a sewage treatment plant, you have to go to a state/local Public Utilities Commission and ask permission to raise your rates to cover it, which can take a long time for review and approval. Imagine doing this every time you want to buy a new OC-3, refresh your CPE/modems, or install new wireless towers! Network upgrades will slow to a crawl. Being a regulated utility is good for steady state maintenance and uptime but bad for capital-heavy upgrades and investment.
People forget that even though the old "Ma Bell" phone network was regularly upgraded, that wasn't because of regulation. Ma Bell was actually a business with a regulated/utility portion (local phone service) and an unregulated portion (long distance and other services). For decades, the unregulated part of their business made enough money that it effectively subsidized the regulated local phone service infrastructure and upgrades. When Ma Bell was broken up, local phone service rates actually went up because the ILECs no longer had the unregulated, profit-making businesses to subsidize them. And it is entirely possible that the same thing would happen if ISPs were treated as utilities and were not using TV, phone or other high-profit services to subsidize Internet access.