The government entities that I've known of building middle or last-mile fiber infrastructure have reported that none of the incumbent operators wanted anything to do with it. Not during planning, construction, post-construction, etc.
If your whole model is monopoly services (att/verizon/cabletown) why would you bother entering a service area where you might have competition? (and an operational model which is radically different from your other properties)
I don't think it's necessary for the 'incumbent telco' (or cabletown) to need/want to participate with the municipal dark-fiber-equivalent deployments, is it?
All that's needed is a couple (one to start) local 'isp' that can service what is effectively a light-duty L1 and ethernet plant, and customer service(s).