The problem here isn't capitalism so much as scarcity. I personally really, really hope that we don't still exclusively practice capitalism once scarcity is eliminated. But those immortal corporations won't like it.
Scarcity is impossible to eliminate. Even if you got rid of all of the costs of production, there would still be limits on human creativity and time. Even if you made infinite ai, so that creativity was unlimited, and made humans immortal, so that time was unlimited, people would still be forced to make choices between alternatives. And those choices can either be voluntary or coerced. Which way would you like to spend your infinite life? It's not communism if you aren't forced to share. It's capitalism.
Capitalism really is a bad term anyway. Marx invented it so he could use it for his straw-man arguments. But really it should be called free markets, or freedom, or opportunity, or the American Dream or something.
