I think it'd be great if the two companies keep 2 stations from each decade. If they want to run one of those two channels form each decade on the cheap here's an idea that many of us will love:
One of the 70s channels will include some of the best jocks of that era live 24/7 while the other one will run old countdowns of American Top 40, and even some of the local countdowns (like WABC, WLS, Boss Radio, etc.).
Same deal with the 80s decade: Have one of the channels combine all those bigger then life jingles and liners from Z-100 and other famous CHRs, throw in some top notch talent, while the other 80s channel will feature nonstop countdowns from Casey and Rick Dees, and even old MTV countdowns (I know I know, they aired on TV, but would still be cool to listen to on the radio), and you could even run Backtraxx USA on it. I also think you could run other specialty programs on the other 80s channel, like mixshows on the weekends featuring the music of Hot 103/97, Power 96, DRQ of the early 80s, Power 106, etc.
I mean really, there's no need to can some of the decades channels - it just leaves more room for creativity when you have two 60s/70s/80s channels rather then one
I also think that with the upcoming merger XM and Sirius will continue to grow as far as the number of subcribers are concerned and as such I don't think any of the shock jocks should be let go. It's just that some of these jocks may need to think more outside the box and present their shows in a more unique sort of way so as to differentiate themselves from one another. Males in particular love listening to jocks who are bold, daring, and yet at the same time they can relate to. After all, shock value radio sounds best when its untamed and uncensored, and only satellite radio nowadays can give us this brand of radio.