This would weirdly exert a greater downward pressure on salaries, as companies will have a higher supply of higher skill workers rather than just workers as a whole.
Right now H1B are equally exerting downward pressure on salaries at the top, middle, and bottom of the market. Salaries then in turn are falling by a relatively equal amount for everyone. If it is only targeted at the top, that hurts the ceiling for with people in the industry can earn.