As I see it, there are three viable political choices out there, but the two party system obscures the unity of the third.
The first, as you say, is nationalistic populism (Trump supporters).
The second, as you say, is the Far Left - economic socialism combined with social radicalism.
The third is the political establishment, a model of crony capitalism with trade and immigration policies that favor the international elite. Politicians in this category can either pay lip service to conservative social issues to steal votes from nationalist populists (establishment Republicans) or side with the far Left on some social issues while being in bed with Wall Street and Silicon Valley (establishment Democrats). Both Jeb Bush and Hillary Clinton are therefore in the same party in everything but name.
“As I see it, there are three viable political choices out there, but the two party system obscures the unity of the third.”
I think I would have voted for Bernie over Bush in 2016. Four years of Bernie and a chance of someone better was a better choice than the best being Bush for 8 years.