My take on the situation:
IMO Ganguly is the best captain India have had for quite a while, and he seems to get on well with John Wright, who is surely India's best ever coach.
Hence, while he may not get into India's absolute best Test XI, his just-about-reasonable batting combined with his superb captaincy should keep his role as it is. I certainly think it is better with him at six and Laxman at five.
Ganguly's place in the ODI side is not in question.
Mohd Kaif should be behind the option of Sehwag at six and Yuvraj Singh, as he has already had chances in the Test-side and failed, while Yuvraj is making his debut and Sehwag averages something like 43 at six. Sehwag, meanwhile, held his form for Leics (averaged over 47 in FC-cricket) while Yuvraj was dismal for us, in both forms of the game. Kaif also had a disappointing season for Derbys in the FC-game.
So, summing-up, Ganguly's good captaincy is not something India can afford to give-up unless Ganguly's presence is actually hindering the side, rather than just not helping as much as Sehwag at six would be. If the Test-captaincy is forced to be transferred, personally I would go for Sehwag not Dravid or Tendulkar. I don't think he would make any worse captain and somehow his batting strikes me as the type that it's simply not possible to be bothered by captaincy.
RIP Fardin Qayyumi (AKA "cricket player"; "Bob"), 1/11/1990-15/4/2006