I don't disagree that blocking was the right choice. What I question was whether Comcast's current monopoly practices in the face of pressure across all business sectors (some more than others) are enough to make this merger make sense as a strategic business decision.
2-3 years ago where I live, you had a "choice" of high speed Internet -- DSL from CenturyLink, permanently stuck in the sub-2 Mbit/sec range or Comcast at 10+. A local Internet provider has been wiring part of the city for fiber -- it's a pretty small area now, but they just announced an expansion and are even offer 10 gig. CenturyLink has been running fiber in residential neighborhoods over the past month.
So by the end of the year, it's possible that there will be far better choices than Comcast for high speed Internet. Obviously this isn't enough, only one place, limited availability, etc, but it shows that other providers "get it" and see that Comcast is ripe for the picking.
I think the pressures on Comcast's cable TV service are even greater from Netflix, Amazon, HBO's new streaming option, selective download services like iTunes, Roku "channels" and so on. You can get most content now without cable.
I'd be most worried if I was Comcast about the original content. Most of what underpins cable is having content, and it may not be unlikely that in the near future the content people want isn't even available on Comcast or any other cable service at all.