As Crabcake pointed out, see Italians and Irish people who were at one time seen as non-White and their Catholic religion that the "'White' conservative Christians WASPs" found totally unacceptable make its way into the mainstream with ease.
That is not true. Italians and Irish were always considered white, even if discriminated against. During segregation they could use white facilities. They weren't banned from marrying WASPs under anti-miscenigation laws. The Census didn't have any separate categories for them. The idea that just because some ethnicities faced discrimination at some point automatically means they weren't considered white is absurd.
But there isn't a separate category for Hispanics on the census (or so I've heard) and yet popular consensus places them in a sort of halfway house between white and not white. With the fact that Hispanics will presumably assimilate and lose their Spanish language roots, while intermarrying significantly I somehow doubt that whiter Hispanics will be excluded with white category given time.I'd add that it's not clear that all of them will end up in the same category. My nephew's father is Cuban, so for Census purposes, my nephew is "Hispanic". Yet he looks as white I do, and it seems ridiculous to imagine that anyone would regard him as non-white....despite the fact that his father does not look at all white, and presumably does not regard himself as such.
So, point is, blindly looking at these population growth projections for "Hispanics", as if all of them are going to be regarded as being in the same racial category, seems rather suspect to me.