I doubt we could possibly make any grand leap to the left, even if Sanders was elected. He can only do so much with executive orders. He wouldn't get to make laws or even allocate the real budget without stealing money from somewhere else, like Trump. In fact, I think the Democratic majorities in congress might even rebel if Sanders got too far out there.

What you are worried about could only happen if a whole new slate of Socialist and left-wing Democrats got into congress at the same time as Sanders was President. How many Socialists, Social Democrats, and Democratic Socialists are there in congress? Three? And one of those is Sanders.