I don't think anyone is saying whites becoming a minority topples white supremacy. But a larger voting demographic will absolutely have a better opportunity to influence policy. Look at the polling, if the country were a majority black and hispanic, is there any doubt that Hillary Clinton would have beaten Trump?
So we could have had Hillary?!
Seriously though, should we use immigration to alter election results? And if so, shouldn't citizens here already have a say in that? I've never heard a politician ask if we should import more Democrats.