Rephrasing the original question: if we can anticipate the guiding principles underlying the morality of the future, ought we apply those principles to our current circumstances to make decisions, supposing they are different?
Though you seem to be implicitly assuming that the guiding principles don't change, merely the decisions, and those changed decisions are due to the closest implementable approximation of our guiding principles varying over time based on economic change. (Did I understand that right?)
Pretty much. Though it feels totally different from the inside. Athens could not have thrived without slave labor, and so you find folks arguing that slavery is moral, not just necessary. Since you can't say "Action A is immoral but economically necessary, so we shall A" you instead say "Action A is moral, here are some great arguments to that effect!"
And when we have enough money, we can even invent new things to be upset about, like vegetable rights.
Here's the new thread for posting quotes, with the usual rules: