[Luis Gonzalez]

"...500,000 years from now, even if man is wiped out in the next 20 years, the evidence of man having been here will still be unmistakable and irrefutable."

But not in 2 to 3 billion years, a relatively short period of time in respect to the Earth.

[AntiGuv]

That's untrue. The evidence of man having been here will still be unmistakable and irrefutable in 2 to 3 billion years, it'll just be more dispersed and slightly harder to dig up.