Jay Leno is only one of two entities printing money for NBC (the other being news). Jay himself jokes of the bad state at NBC during his show. He also jokes that NBC is screwed if the Olympics have low ratings.
Conan has a younger audience base than Jay, and that is what NBC wants to sell to. NBC believes that things will be better with Conan in the 11:34:30 time slot in the long run. I am sure NBC will throw money at Jay to stay. I just wonder how Jay Leno in the daytime would work out.
As for CBS...I don't expect another 1992 all over again. The reason Jay Leno is going quietly (at least publicly) is to prevent another 1992 (where Letterman was set to succeed Leno, only for Leno to installed temporarily then permanently, and Letterman defected to CBS in protest).
As for ABC...Unlikely. Jimmy Kimmel (after winning a battle to be on in Atlanta) has even younger demos than Conan. While I do see Nightline going away soon (I don't know how it is doing after Ted Koppel left), I don't see Leno there.
As for CNN...given how they gave Glenn Beck a show (on Headline News), a comedy show on CNN might be a refreshing change of pace. Seriously...Jay Leno is a comedian, not an hardcore interviewer like Larry King. Jay Leno replacing Larry King is out.
As for Fox...don't see it given Fox's younger demos. If so, 11 PM start time is out due to local "News Edge" newscasts at Fox O&O's. Also, Jay Leno belongs to the Keith Olbermann club of "Fox Noise/Fixed News/Republican Headquarters Channel", so I don't see Jay at Fox unless he can make fun of Fox and Fixed Noise.
Syndication...another option, but no. He would be on CW/My Network TV/Independent stations without the clout of the major network affilates.
Cable is another option where he might go. I don't see Comedy Central (the obvious choice to most), but TBS (with its emphasis on comedy) or USA or Bravo (under an NBC deal) would be possible choices. TV Land is another option.
The most likely option is retirement from TV and doing stand-up full time. He does not need the money (he either saves or donates to charity his NBC pay), and he would have more opprotunties to do stand-up (he is tied to NBC's Burbank studios most of the year because of the Tonight Show...his time off is spent on stand-up tours).
My money is either an NBC deal, TBS, or retirement from TV.