But there are other trombone players in the country, google will just have to pay them more than the competition to get them and/or the competition will have to raise their pay to make them stay. In the long run, some orchestras might be a trombone player short, but with high(er) average wages, you'll get more people who take trombone-playing as a career path.

There are very very few positions, that you can't fill if you offer above-average pay and working conditions, and most H1B visa carriers now, are not unicorns, but usually just someone willing to work for less money than locals (example: https://www.nytimes.com/2015/06/04/us/last-task-after-layoff... )