If you think long term, like Asimov and the turgid and unreadable Stapledon (and maybe Tsiolkovsky and Kardashev in the Russian take-it-seriously school of futuristics) were among the first to do (I discount Doc Smith), it's obvious that there really are no other choices. Interim solutions, such as "empires" and other such nonsense, are doomed to failure. (Not that I endorse any of these people's vision; I think all of them, in their own ways, were unaware of certain important factors or failed to really think through some of the implications).
This is indeed a more or less Marxist view of history. But I'm convinced it's true. Global capitalism is the grand experiment in using a system that relies, in theory, though not practice, on "enlightened self-interest." It is failing, and will drag the entire species down with it if people don't wake up and change the course of history in time. Stay tuned. No one yet knows how it will turn out. I believe, but cannot prove, that "self-interest" in this acquisitiveness-oriented sense, as an ethical basis for organization of societies of sentient beings anywhere in the universe, does not and cannot work. You call it guilt, I call it cooperation. And it's the only way. Ants probably have a better social organization than we do, but I think intelligent beings are always messy. They have to be free to think and experience. So there has to be a lot of flexibility. But at the core there has to be mutual benefit cooperation. Or else, collapse. No other road.
I am cautiously optimistic, and I'll tell you why. I think that the advantages of socialization of well-being will become so obvious, assuming we survive the Fossil Fuel Interval and reindustrialize using purely renewable resources (an obvious necessity), that the theory will become so widely accepted it'll be treated as fact. Then, over time, civilization can build institutions with checks and balances that guarantee a degree of stability. Something like this has happened many times before, but here we're talking about the first real global cooperation. What makes me optimistic is that once that is working, its advantages, I believe, will be so obvious to everyone that there will be no going back. Of course there will always be rogues and rebels, but there will also be a slow and steady progress towards a permanent economy of Abundance. And that will change everything.