You should read the entire article. Toba hasn't held up well to additional evidence. It was certainly hell for many in the area, but it doesn't seem to be the bottleneck that people still quote it for.
Life in general does rebound, it's very persistent. That doesn't mean most life won't die off, nor will the rebound be quick and even resemble what we had. My own opinion is that we may have been witness to the peak of biodiversity, something that won't even happen at that scale again simply because it needed specific conditions to be so vast.