Wow, this story sounds like the most solid rumor yet! I'm actually getting a little jazzed about it.
This may sound crazy, but Mad Men strikes me as something very similar to a Star Trek format.
Not so crazy.
Pan Am is pretty obviously inspired by
Mad Men, and I've noticed a distinct similarity to
Star Trek, especially since it's based around a crew on a form of glamorous transportation which lends itself to both weekly adventures and overarching plotlines.
The actors and (with some tweaks) the characters could be ported right over to a
Star Trek series and work out great. They'd have to add a few actors who aren't lily-white, of course, but that's easy enough.
On the topic of whether CBS would be interested in developing
Star Trek for a channel they don't own,
here's what CBS Studios is developing for 2012-13. It's all for CBS properties (CBS, CW, Showtime) except for one for TNT.
TNT is very interesting to me...it's got the cable advantage of not requiring a huge broadcast audience for success, but it's also kind of broadcasty in that it doesn't air the hard-edged or risky shows you might see on AMC, Showtime, HBO or FX, but rather opts for shows that could very well air on broadcast, like
Falling Skies.
TNT is just about the perfect location for a new
Star Trek series. The success of
Falling Skies shows that their audience likes aliens!

Pair up the two shows or air
Star Trek in the fall in
Falling Skies' summer timeslot, and I bet they could get more or less the 6M number that
Falling Skies does. They'll have to watch the budget, but it sounds doable.
Another less probable option: CBS Studio makes the show for NBC. In general, I don't think
Star Trek can survive on broadcast anymore, being too pricey and too nichey, but NBC is desperate for anything that makes noise because their main problem now is that everyone has stopped watching their channel entirely. Hard to advertise new shows when nobody watches the old ones.
NBC's pilot lineups for next season are very high concept - there's a Western and a few genre shows including one from JJ Abrams and another that sounds like a
Caprica do-over.
Star Trek would fit right in, and give a big PR boost to their whole struggling lineup.