The desire to come and immigrate to the US has greatly diminished. This use to be a easy decision for foreign students to stay in the US for work opportunities. Nowadays, a US degree isn't considered prestigious outside of a few elite schools and the cost has completely spiraled out of control. I've talked to numerous colleagues who abandoned waiting for a green card because it's no longer a clear cut decision. Opportunities and quality of life in other countries have either caught up or surpassed the US in certain areas. This would of been unthinkable 10-20 years ago.