Even with Mestizos many have a large European genetic source.
If immigration was slowed down, the Latino community would actually have the chance to assimilate. Not all of them would assimilate into the “white” category like Eastern Europeans, Italians, and the Irish did, but a good amount would to render the category useless.
The fact that we are effectively redefining the white race to allow for mongrelization a la Latim America proves to me that we are a Third World country.