The are sort of partners already anyway right?
I'm not a conspiracy theorist, but Echostar head Charles Ergen is a...how should I put it...scrappy, shrewd guy. I would not put anything past him.
Yes, the ground repeaters are interesting...and Dish is a distant #2 to DirecTV However, don't forget that Dish is an experienced satellite service operator. Who, given the opportunity, may find a way to operate Sirius XM successfully. A lot of the debt would have to be re-organized and/or converted to equity, however.
I am not sure that the FCC would have a whole lot of problems with this...other than perhaps trying to get some more concessions to minority interests.