Give them a couple years. After a few more "government is bad" TV spots, and under a republican president, they will try again. Whether they merge today or then doesn't really matter.
They are effectively merged already. They stay away from each other, treating customers like each other's property, and offer comparable services at comparable prices. They aren't in any real competition with each other. I'm not saying that they should merge. Rather, I'm saying that them not merging isn't a quick fix of the underlying issue. Americans need actual choice of providers within a given technology.