Expectations of what? There are some people expecting be lifted to the sky by a dead man on a stick, so they can watch from above their fellow human beings suffer from unspeakable perils. There are also others who expect that the guy who has not held a single political office in his life can get out the blue, say a few magic words, be elected president of the United States and everyone will be living happily thereafter. These do not strike me as particularly reasonable expectations.
What irritates me is the people who believe in a dead man on a stick beaming them up are able to pack public offices with politicians sympathetic to their cause without wondering if these politicians will be "left behind" in case of rapture. The lefties, otoh, will not compromise their ideological purity and will support a candidate who is not fully kosher.
I consider it very unlikely that the US will change its politics even if Karl Marx were elected president. I think Europeans left came to that realization in the 1930s as evidenced inter alia by the writings of Antonio Gramsci. The main reason for that is the so-called "civil society" or a web of institutions and more or less loosely organized interest groups that can function more or less independently of the government. There are limits what a government, and a political candidate can do. It takes wisdom and maturity to recognize these limits and support a candidate who has the best chance of delivering the most of what can be obtained under the circumstances.
Some may call it low expectations, I consider it realism.
Wojtek