First of all, the most endangered species might die off with man gone as it has been man that has enabled the re-population of several endangered species...
Secondly, pollution was here BEFORE man, it will be here AFTER man... The planet STILL has volcanoes, there are STILL catastrophic earthquakes that bring up some rather peculiar gases from the Mantle of the planet...
Mars, later this summer will be the brightest since 250 years ago, so light pollution will not be dimmed all THAT much!
Anyway, Venus has so much pollution on it nothing can live there.. We did not cause that. The only thing that will be missing, if man was gone this instant, is man...
Ciao, CZ