The whole point of the phrase is: When the poor have nothing left to eat, they will eat the rich.
It wasnt coined as a threat. It's a warning. The poor are already starving, and there is a limit.
And the thing is that 'rich' is not an intrinsic property, it's not genetic. When you eat the rich, everything they were hoarding - that which gave them the title 'rich' - becomes accessible. It doesn't disappear from the system like an MMO inventory.
Only after the starving poor eat the rich, will there be a path to a possible future without starvation.