There may not be much of an idealistic Left to drive us that way, but the forces of pragmatism may do much the same thing. There are a lot of people who want stuff that works and makes sense. If Medicare For All offers a much cheaper solution, it could happen. If enough people figure out income disparity wrecks the economy, we could reshape the tax system. If we realize we are falling behind the rest of the world, we could see free higher education for the qualified.
Most progressive goals actually are better than the conservative vision, and eventually the truth will out.
Just look at the current state of cannabis legalization! As more and more old white people discover it helps them, it becomes more and more legal. We've come miles from Anslinger telling Congress: "Marijuana makes Negroes think they are as good as White Men."