On the other hand if 100% of india works in the US, you're back to the reason why you left india, in another land. It's a bigger issue than an immigration issue, and honestly I don't think it's solvable (til machines supersede humans of course).
1. Almost all people who are trying to leave India are highly educated.
2. Most of them don't plan to stay outside India for long time.
3. Large percentage of them go back to India when they have a girl child (contrary to popular western rhetoric about 'we are so great they are so bad', women in India are several times safer than in USA).
4. Another large group goes back to India once they have paid house loans, earned enough money, have ailing parents that need help. (India doesn't have a social security system.)
5. A large group of Indians who end up staying 'abroad' are from very specific areas of India (5 out of 29 states of India - Punjab and 4 states of southern India).
6. People from Punjab suffered a cultural shock during partition of India in 1947 and so they see little value in blind nationalism. Most of them are doing business and are not necessarily highly educated (I mean disproportionately). They accept westernization with open hearts.
7. Southern states don't appreciate Hindi being promoted by a Delhi based government - imagine Texas where everyone spoke 4 different languages but not English). So they are prone to moving out for prosperity. They are mostly highly educated. Most of the 'talent companies' like Infosys etc. are being run by them because they generally keep good ties back home. In general no love for westernization. Apu from Simpsons is their caricature.
In short - the degree of success for an Indian in America depends on his support structure. Some communities have built it by being quite and bringing over the family, others have embraced westernization. Both require sheer perseverance. But for large number of Indians, it is simply easier to go back rich and enjoy respect from peers back in India.
Do you mean the birth of a girl child is a trigger to go back?
"women in India are several times safer than in USA"
What measure are you referring to?
Not diversity. US immigration laws have never been designed for diversity. The history of US immigration law is littered with incidents of xenophobic immigration laws targeted at Chinese, Japanese, Irish, as well as East and South Europeans.
Usually the argument for capping or blacklisting immigration from specific nations relates to low observed assimilation rates among immigrants. I suspect that's mostly why most Mexican immigrants to the US use their family contacts in the US to get their immigration requests processed.
[1] https://en.wikipedia.org/wiki/History_of_laws_concerning_imm...