Just a point of clarification during this debate.  The real reason CBS picked up Medium was CBS/Paramount produces Medium.  So, it's their own show.  It's the same reason My Name Is Earl could end up on Fox.  Fox produces that former NBC show. 

Had NBC not cancelled Medium, CBS would have only cut one show from the Without A Trace/The Unit drops.  Warner Bros. produces without a trace, and in years past, it likely would have moved to the WB network, but that is now defunct.  The CW is actually owned by Viacom, the company that owns CBS... so it's like a second CBS network.  As for The Unit, Fox produces that.  There's always the hope it could end up on FX or if Dollhouse continues to tank, it could be revived.

Also, for you Jericho fans... the show will live on in comic books.  In October, the first issue of Jericho: Season 3 will be released.  The show's creators and writers crafted a full seasons of stories to continue the show in comic form.