If there really is a deep division within the Democratic Party (Dean/Gore v. Clark/Clinton) then there is only one strategy that will work for the Clintons:
(drumroll)
Dump Clark and endorse Dean.
If Hillary really wants to set up her 2008 bit (if the conspiracy theorists are right) then she has to get on the Dean bandwagon NOW.
If Dean loses by a fraction of a percent, Gore would inherit the Dean mantle in 08. All the internet folks like me would be hella pissed off and ready to work harder in 2008 to win.
That would give Gore an edge over Hillary in the primaries.
If Hillary wants to mute that advantage, she has to endorse Dean before the primaries.
It only makes good political sense.
Of course it will get messy if there are 3 Democrats in the 2008 race: Hillary, Al, and Howard. Then, it's anybody's race.