Fortunately the FCC did allow the Sirius XM merger and prices did indeed drop (to $7 for a 50-channel plan).
I don't think the prices were lowered; from what I saw, they went up. I can find no mention of a $7, 50-channel plan on any Sirius-XM site. The closest they advertise is $10 for 50 channels of talk or 70 channels of music.
And, like the airlines, they added some mandatory fees to their offerings rather than raising their rates: If you want a plan that includes music, you have to pay the "Music Royalty Fee" (currently 9.8%) and an activation fee.
So no, I don't see the merger helping at all. Just like cable TV, satellite radio could benefit from from good, old-fashioned competition. Corporate management is paid to maximize return on equity, and will charge the highest prices the market will bear.
And there is nothing wrong with that--it's the way business works.