Nothing will happen unless a merger is approved. They dangled that carrot to get the FCC to remove opposition. FCC head Kevin Murphy has a hard on for a la carte, and it was meant to sway him towards the approval side (or at least away from the opposition side)...
The Whole Foods merger that the Justice Dept. tried to block, was allowed by the courts to continue after Justice was overruled since the two natural foods chains were grouped in with the supermarket, um, market, and not just the natual foods market. Many widely read this to mean that the courts would similarly view XM and Sirius in the larger picture that included terrestrial radio, Ipods, and every other car based system fighting for "ear-share".
I especially like one of Mel's comebacks...... After the NAB screamed bloody murder about the "monopoly" it would create, Mel shot back that IF that were the case, then they shouldn't care as a monopoly has no competitors (and WHY are you fighting so hard to weaken your, um, NON competitors). If terrestrial radio is competing with satellite radio, then they just proved Mel's point, that no monopoly would exist.
Meanwhile, Wall Street is starting to sense that this thing might come off after all..... Jim Cramer (yeah, the screaming stock picking guy), just made Sirius a "buy" after being down on the stock for 6 months.....