We know that life on Earth has never been reduced back to single-celled organisms since at least the Cambrian, 600 Ma past. The geologic mass extinctions always left some macroscopic and complex life, each time.

Of course, this is not inconsistent with an average survival time of "a few hundred million years", but it's a bit more hopeful.

Nonetheless, there are many dangers to a technological civilisation, and they appear to get worse with time, not better. For instance, pre WWII we could only "hope" to extinguish individual nations and races. In the atomic era, governments gained the power to extinguish the entire human race and all mammals too! Today, special interest groups such as Al Queda are working towards that capability.

This is how the world ends, not with a bang, but with a sniffle...