There already has been a near-epidemic of the flu-like coronavirus, SAARs. It could have been the fatal epidemic. Bird flu is just another.
But as we can see from both, we're a bit more prepared for epidemics now than we ever were before. They can be controlled, if caught in time, and the virus doesn't get its chance to hit major populations and mutate into even deadlier strains.
And we live differently these days too. Not many people live in close proximity to birds. I mean, you might have them in your garden, but you don't live with them. During WW1, people lived in cramped, filthy conditions with livestock in the trenches - an ideal environment for these viruses to mutate. There was a huge flu epidemic in 1917 that killed millions, and it was no coincidence many believe.
As long as there is no major war, and people live apart from livestock, and there is the technology to trace people as they travel around the world, we're well protected from a major outbreak. It might still happen, but we're safer than we used to be. I don't think this "it goes around every 40 years!!" mantra really makes much sense. If that kind of thing were true, I'd have spent the 90s fighting another world war.
