Really the key isn't more regulation but the Sherman Act and related anti-trust laws that are clearly being broken, often abetted by local government.
One way to do this is to force the current monopoly to provide it's services at cost to competitors who can then sell value add on top (this is what we did in the UK with British Telecom (though the different here is that BT was nationally owned)) not sure if you could do that in the US since comcast is a private corp.
This worked reasonably well for long-distance services (those used to be separate from local phone service) but the advent of high-profit DSL meant that the local monopoly would prioritize fixing their own customers's lines over their competitors, and perhaps do difficult-to-prove-intent things like repurpose competitor copper during a field repair, and then never put it back.
Around here, Comcast (or their predecessor) actually does resell other providers' services through their service. I don't know if it's voluntary or not. It's kind of an odd relationship, but I'm happy to divert a few of my dollars from Comcast to Earthlink.
I use sonic.net here in SF and I think they work in a similar way by piggybacking on the ATT local loop. I wonder if there is any local law that forces ATT to co-operate in that case.