"The question is, can left-wing populism really beat right-wing populism?"

Maybe.  Maybe not.  But then where will all that big corporate money go? One of the two parties will be bought out. Then the other party will do the same to compete.  And the snake will continue to eat its tail.

Trump could start to drain that swamp by appointing justices who would do away with Citizens United and allow campaign finance reform to take place.  But he won't.  He'll hand those appointments over to the evangelicals so we end up with a theocracy.