Roadtrip,
It is not the school that is the problem. I have extensive experience in flight school business. It is infrastructure and airports in India. The students will have to go for cross countries, or practice ILS approaches for their IR training. I didnt realise how luck we were in USA until I came back to India. I fly for an airline and we still shoot full VOR approaches in non-radar environment. If you are a student pilot and practicing landings and an airliner approaches you would have to call it a day.
Most (cant say all, that is the counselers job) student pilots will come back to India. When you are only 18-20 years old and you can make $3500 per month and are treated like a king why wont you come back. I dont think they want to stay back in the states to pick oranges or work at gas stations or motels making $6 per hour. So you dont have to worry about people staying back. It is a different story if someone who wants to desperatily move to USA uses aviation to get in the States. But thats where TSA, and US embassy expertise comes in.