There could be some synergies between Ergen's Echostar and SiriusXM that bode well for the future. Call centers, accounting, things like that. Maybe even the respective satellites.
However, one of the things many of us like--maybe love--about satellite radio is the anything goes, uncensored nature of certain channels. Ergen doesn't seem to be on board with this quite so much, if Dish Network gives us a clue.
For example, he will not permit Logo, the gay TV network, on any tier of Dish Network. On most cable providers and DirecTV, Logo occupies either first-tier or second-tier channels. Logo is not X-rated, but it is risque. On cable and DirecTV, up until midnight, they censor George Carlin's seven words--and more. If Ergen takes over, I'd be concerned that he'd kill Sirius OutQ, just as its audience seems to be building once again, just because he's "prudish."
Beyond that niche, there are plenty of other non-music channels (besides Howard) that currently enjoy wider-than-terrestrial freedom of speech. How would Ergen's ownership affect those? I think we have a clue. Everything from Cosmo to Road Dog to Raw Dog to Foxxhole and more would be in jeopardy IMHO.