Why would they scuttle it? They'll give a few token concessions and continue to screw consumers. The only way to win in this game is to invest in these monopolies.
"In April 2015, it was reported that the U.S. Department of Justice was preparing to file an antitrust lawsuit against Comcast and Time Warner in a bid to halt the merger, arguing that the merger would reduce the level of competition in the cable television and broadband internet industries. On April 24, 2015, Comcast officially announced that it had called off the merger."
+1 I'm not sure if they're allowing this through for upper-tier competition.
Although when you have a deal this large, the law firms are bound to be well connected and will be pulling every string they have to push the deal through.