I don't really know how I feel about the acquisition. I think some of the things Krugman talks about -- e.g., no incentive to upgrade networks -- certainly has validity; I also know that we *HATE* network congestion, and just in my unit, alone, spend tens of millions a year to avoid it. Of course, without incentive, that's just 'cause we feel like doing that, not because we have to.
The one that has me really, truly worried, though, is Net Neutrality. I am *STRONGLY* in favor of the FCC saying "F*** you all: it's time," and pushing it out. I think that neutrality, combined with the rise (and eventual commoditization) of cellular networks, as well as good ol' Ma Bell and DSL, will be able to offer competing solutions. Of course, then there's satellite, as well, but the inherent latency makes that a poorer option by definition.
Comcast is, however, essentially right: they don't compete with other cable companies because of the infrastructure; one thing that might be interesting -- though I have a sneaking suspicion Republicans would cry foul about over-regulation all day long -- would be if the gov't enforced a move akin to the telecom and power companies: if cable companies could offer the landline connection, but you were able to get service from anyone. That would go a great way toward leveling the playing field.