The immigrants, who have a good chance to become middle class Americans (as did most of our ancestors).
Their employers, who get hard working and highly motivated workers awed by what to them a very high salaries.
If you look at major league baseball, not the improvement in the quality of the game due to immigrants, who appear to win over half the positions (in a very objective, skills based competition).
As most of the immigrants now are social conservatives, from societies that that are conservative in sexual matters, pro-life and anti-LGTBQ, it isn’t so clear if they’ll end up as Republicans or Democrats (though by the time they become citizens, the parties may have realigned). Also, most of the Hispanics coming are fleeing countries with socialists governments, rigged elections and courts that decide cases politically based on rule of law, so they might be disinclined to support the Democrats as they now are (which will really confuse those who hold by “intersectionality”).
My guess is that the current wave will support rapid economic growth in the USA in spite of a low birthrate, have no impact on politics but might force both parties back to the center, and that in a generation or two the “nativist” movement to keep out mass immigration will be led by Hispanics (just as the current anti-immigration movement is led by the descendants of those who came through Ellis Island).