Cuckservatives are always creaming over the Latino/whatever vote.

Indeed, and that crossed my mind when I composed the comment. The whole 'natural conservatives' meme. I didn't bother mentioning it because it seemed intuitive that if the Biden Administration was the one who amnestied them, they would be clearly be beholden to the Democrats and not to the Republicans because of the actions of these treacherous Republicans. A Republican would have to be particularly dense to think that the Democrats amnestying illegals would help Republicans more so than Democrats.

Republicans are not going to be the party of white people.

I think their voter base will become, say, 80-90% White, but the GOP will never be pro-White, i.e. it will never become an ethnonationalist or nativist party. This is probably what you mean in your comment: the GOP will never use its 'implicit Whiteness' as a strength, and will always see it as a disadvantage needing rectification by doubling-down on its appeals to other races.

Since the GOP, I suspect, will never be able to attract large numbers of any nonwhite group despite doubling-down on their efforts to do so, they will simply decline into obscurity under a de facto Democratic dominant-party state.

Yes, you're correct in the last paragraph as well: The current crop of Republican politicians probably by and large have no party loyalty and thus by extension couldn't care less about whether the party can still get elected on the Federal level. They'll still be elected in the lesser levels of government for perhaps decades to come, although things will turn against them there too (and the signs of that are already clear in Texas and a few other 'purple', formerly Red, states).