Umm.. It's a rather huge leap between "tens of millions" and two billion deaths!
One thing of note from the article is that viruses tend to mutate into less lethal forms. It does a virus no good to kill off its host.
So eventually the bird flu will develop into less virulent strains that will spread through birds easier without killing them and the lethal forms will stop spreading and will be replaced.
But that doesn't mean the "less lethal to birds" virus will be less lethal to humans. It might be that the milder virus just spreads easier and at an undetectable level across the world while continuing to kill off people and continuing to mutate into forms that can infect humans easier.
We really need an effective, easy to manufacture vaccine soon.