Ultimately...life will recover: it always has. The mass extinctions of the past offer hints as to how the ecosystem will eventually bounce back, says Mike Benton at the University of Bristol, UK. The two that we know most about are the end-Permian extinction 252 million years ago, which wiped out 80 per cent of species, and the less severe end-Cretaceous extinction 65 million years ago, which famously took out the dinosaurs. The Permian extinction is more relevant because it was caused by massive global warming, but Benton cautions that the world was very different then, so today's mass extinction will not play out in quite the same way.
Recoveries usually have two stages. If ours pans out in the same way, the first 2 to 3 million years will be dominated by fast-reproducing, short-lived "disaster taxa". These will rapidly give rise to new species and bring the world's species count back up-- from Will there be any Nature Left?, part of a package on the Deep Future. I'd say the future is likely to be less predictable, especially given the human tendency to meddle and manipulate.