In about a week it would appear, this matter would go away. Nobody would be tried. India would give up more and receive less but claim victory. India is not China or Russia where man for man they would have already arrested an American diplomat.
Indian politicians are less worried about the diplomat's insult, they are more worried about their own personal affairs. Prime Minister Manmohan Singh is a pocket toy of American (his family would prefer to settle in America), Sonia Gandhi keeps coming for treatment to New York. She does not wish to loose that privilege. Her son Rahul Gandhi was lackluster student in US and graduated only because of the patronage of the American Government. Every Indian politician or high official has a kid or immediate interest in US. They do not wish to jeopardise that by acting tough with the American diplomats in Delhi. The only reason they are giving the appearance of acting tough today is that in this internet and modern age, the arrest and cavity search (reserved for gun runners and drug smugglers) of Indian diplomat could not be swept under the rug. People in India were up in arms. With federal elections round the corner, the politicians did not wish loose any more votes.
If an American diplomat is arrested for fraud, conspiracy and lies, in New Delhi (which may happen, because Americans are not the most honest people), the only reason the current government would be doing that is to please the people. They are aware that toughness could bring them votes back, which they lost in last month's provincial elections.