Well based on recent world events it could be quite soon!!
All joking aside, its a good question! Nobody really knows the answer, Though as the human population continues to expand, whilst feeling the effects of climate change making food more scarce and land less available, the chances of a mass extinction rise quite a lot! I think the human race will always survive things like that though, there just might be a lot less people around!
We should have a good few thousand years left though, so don’t worry too much 🙂
There’s one really interesting theory about why we haven’t yet discovered any alien life… They say it could be because any civilization capable of developing the technology for space travel will always destroy itself around the same time… (due to war, environmental destruction, bad AI, politics etc). I could see this happening to humans!