The most likely case scenario
Ganguly will play and bat at number six after Tendulkar and Laxman.
He will bat for his life. He will give it his all. Being a test match, time is unlikely to be of great relevance. So I would expect him to play a slow steady innings. Number six will suit him Unless he comes in with the second new ball.
He will play very very carefully, excessively so and may, in between, with second rung slow bowlers (read everyone other than Murali) try to break free with lofted shots.
Sri Lanka is likely to attack him with short pitched stuff as soon as he comes in. But if a long partnership has ensued and the bowlers are weary, it may not be effective.
Murali might bother him a bit. But I suspect, the nedium pacers, if fresh, to come at him strongly.
It should be an interesting match within a match.
If he does play, I do hope for India's sake, that he comes good with the bat for that cant be bad for any team.
I hope, also for India's sake, that Ganguly talks to someone with sense who advises him to go out of his way not to make a nuisance of himself, intentionally or inadvertantly, because of the baggage of the recent past.
If he manages both these, we may all be much happier than we are today and happy days may continue.
But...
,,,there is a new selection committee to be appointed in a couple of months or so. The BCCI elections and the new committee could determine more of what happens with team India than all the good performances on the field.
*crosses fingers and tries to rub the furrows on the forehead away+