Are the policies of American political parties realigning to their base?

In This Is What the Future of American Politics Looks Like Michael Lind argues that we're seeing an earthquake in American politics. He argues support for the two major parties will align on policy grounds rather than the current partisan alignment. That is, the Republican Party  has become the party of the white, southern and mid-western working class and we will see it's policies align accordingly (nationalistic, anti-immigration, anti-free trade, pro Social Security and Medicare). He argues the reason Trump has won the Republican Party presidential nomination is because he has espoused these policies.

By contrast the Democrats will become the party of multiculturalism and globalisation.Its support base will be "an alliance of upscale, progressive whites with blacks and Latinos, based in large and diverse cities".