The end of all flesh is come before me. — A metaphor taken from the customs of earthly kings. Before an order is executed the decree is presented to the sovereign, that it may finally be examined, and if approved, receive the sign manual, upon which it becomes law.
I will destroy them. — Not the verb used in Genesis 6:7, but that translated had corrupted in Genesis 6:12. It means “to bring to ruin, devastate.”
With the earth. — Rather, even the earth: eth, as in Genesis 4:1. The meaning is, “I will bring them to nought, even the whole present constitution of earthly things.”