Obviously I can't speak for Trump, but I think it's accurate to say that the criticism of H1B visas is that they've been abused by tech companies wanting to hire foreign workers for entry-level jobs at low wages. The intent of the H1B was originally to attract real talent that we couldn't produce locally, such as specialists, PhDs, and experts with proven talent. The implication for you might be that, if H1B visas are reformed, you'll be less likely to get an entry level job after the masters degree, but should be better able to get a visa and a job in the USA as you advance in your career.