Apparently, Paul Krugman does not think there is a wide diversity of thought in the Republican Party. Oddly the Democratic Party is far more rigid in my opinion on matters of orthodoxy. (What has happened to the conservative Democrat anyway?)
I would venture to say that the class divisions (Democrats working class; Republicans capitalist class) no longer hold. All the talk about the GOP fighting to hold onto privilege is just Marxist, post-structuralist gibberish.
Until Trump the GOP was loosely committed to individual rights, free markets and a robust foreign policy placed under the movement that was guided by Goldwater-Buckley-Reagan. That may not longer hold going forward. And thus the differences between the two parties in a putative Age of Trump may share some overlap.