[zerodensity]

They will adapt or die and something will replace them. Diversity will go down for a while and then back up again. It's almost impossible to sterilize Earth and as long as something lives on it will eventually flourish again. It will never be the same but something else will flourish.

[Theory42]

True, but we're talking about millions of years of possible desolation before that happens.

[sgu999]

Isn't it part of the question of whether life existed on Mars? If it did and got wiped out, it would mean that something else doesn't always flourish.