They would need to be broken up the same way that AT&T was broken up back in the day. The breakups allowed for the sharing of infrastructure by various competitors so that you could call Sprint, MCI, or whomever for (at very least) your long distance service and possibly your local service as well.
You only really competition if you can choose your cable provider wherever you live.
It's very difficult for a start-up cable company or ISP with an innovative product, say, a la carte pricing, to get going because Comcast can undersell them (or offer the same innovative product) for as long as it takes for the start-up to burn through their capital. They can do this because 1) The start-up's limited capital prevents them from opening in every market at once; and 2) Comcast's national presence allows them to use the profits from one region to subsidize service in the region where the start-up is competing. It's probably cheaper to just buy Comcast than to try to beat them in a race to the bottom.
So yes they're a business and of course they should make money, but that needs to be balanced out by the needs of their customers. It might be overdue for cable companies and the phone companies to be broken up. In fact it might be a good idea that they be broken up every ten years or so given their immediate power over consumers.