Whats your take

[busker]

I have a misanthropic fantasy.  All humans vanish.  I am a spirit of some kind that can hover over the earth and watch all traces of human habitation on the planet slowly disappear.  From what I've read, it would only take a century or two.  There would always be some trace of us remaining, but much of what we've built would be swallowed up and disintegrate.  The poisons we've put into the environment would be more slowly purged from its system. 

I suppose some other species would rise up to become dominant on the planet and it would probably be just as or more destructive than humans.  But maybe not.

There are no poisons that humans have put into the environment other than radioactive isotopes. All other poisons - heavy metals and their compounds - were already ocurring as oxides or sulphides before being refined. 
From the earth's POV, the quantity of CO2 in the atmosphere is a fraction of what it was 65 million years ago. I mean, that's how the earth got its load of fossil fuels in the first place - fixation through coalification etc

The only way humanity would disappear in a matter of days or months or even years is through nuclear war or an asteroid impact. Not even an asteroid impact, actually, as people on the other side of the planet would survive on seal meat and berries.