Its a tough call, Ganguly has done really well this whole year and years before for India. His batting was quite good last season and this season, but he has had a bad tour. Every player is human, and they can have a bad tour, but maybe after the WC, If Ganguly fails it is time to re-evaulate his position in Indian Cricket.
For one, I would love to see Rahul Dravid as captain, you can see that the whole teams admires and looks up to this man, he is respected, more-so than Ganguly, who can be rather snobbish and arrogant, he is calm, cool and collected as well, but to criticise him on one thing, he is not assertive and aggressive, but rather meek and mild mannered.
I say keep Ganguly until the WC and after the WC re-evaluate his performance.