I think the model like DSL service should be the one that municipal fiber follows -- the municipal fiber just provides the layer 2 connectivity and you choose which ISP you want.
If somebody wants to start a geek-centric service with static IPs and where technical support is limited to setting reverse DNS, great, they can buy a rack or whatever at the municipal fiber hosting center and sell that service to whoever's interested.
If Comcast or AOL or whoever wants to offer their mega-consumer focused service with dynamic IPs, webmail, coupon offers, ad-injection, great, they can lease a rack, too and sell that.
Plenty of cheapskates and technophobes will pick the consumer service for all the add-ons and technical support and the geeks willing to spend the same or just slightly more for static IP service with none of the bullshit can pick that.
There was a time where a company I knew set themselves up as an ISP choice for DSL. Employees could get DSL from the phone company, choose their employer as their ISP and they had basically a hardwired VPN to work (that solution has some issues in terms of personal-vs-work access, but IIRC from the network guy at that company I talked to they had an entirely separate Internet provider they routed that traffic over). I think whatever setup and operational cost was greatly mitigated by reduced costs related to remote access and the legion of VIPs who wanted their personal ISP bill reimbursed because that "expense" got taken care off at wholesale.
The analogy that makes the most sense is the roads. The city builds 'em, fixes 'em and sets some pretty basic usage rules, but you buy your transportation and delivery services from other companies. If I want a pizza, I pick whoever provides the pizza I want and they just use the road to get it to me.