The planet might be ok after us, but still might not be able to birth another potentially space faring civilization, dooming earth life to extinction.
Look at how:
- no other earth based space faring civilization has evolved before us.
- other intelligent species do not seem well equipped to do so, as it's hard to evolve tools without hands / prehensile organs (cetaceans), or when your lifespan is short or you're not social (octopuses & squids).
- we used up pretty much all easily accessible fossil fuels for our industrial revolution and they may take hundreds of millions of years to reconstitute, and it's unclear if anyone could evolve an industrial civilization without that kickstart of easy energy.
It's far from certain that if we disappear earth will get another good shot at evolving a space faring civilization before it's too late.