I have a small amount of experience with this, having observed the negotiations between a city government and Mediacom. The deal, in that case, wasn't technical

I have a small amount of experience with this, having observed the negotiations between a city government and Mediacom. The deal, in that case, wasn't technically "exclusive", but it did require that any additional franchisee provide equal or better service. In practice, this meant that the deal with Mediacom was "exclusive" since the market was small enough that no other provider would be willing to roll out the full set of services offered by Mediacom (another provider might have been willing to offer basic services to capture cost-conscious consumers). I'm not sure what the federal law says about this sort of thing.