In this case, claims like 'probable', 'highly unlikely' or 'inevitable' are all bogus. The truth is that we do not have any idea how to estimate the probability that this specific H5N1 strain of avian influenza will cause a human pandemic.
What we can say is that based on past experience a pandemic is probable at some point. It may not be this avian influenza that causes the pandemic. It may not even be avian influenza. We don't know. However, influenza strains have been quite successful at mutating over the years, there have been a number of documented flu pandemics that are apparently caused by some of these mutations, and there is evidence that some of the pandemics are caused by influenza strains that jumped from one species to another.
We can also say that the current outbreaks of H5N1 avian influenza make it the most likely known candidate to cause the next pandemic.
Beyond that everything is speculative. We do not really know if or when this strain or some other will cause the next pandemic. We just know (from history) that a pandemic is likely to come. My understanding is that, based on historical records, we are presently a bit past due. Still, that does not mean it will happen this year or next or even this decade.
This one tip will help you sleep better tonight
A few seconds are all you need to get a better night's rest.