I found it was interesting that the noted that hunter numbers did not peak with the recent upswing of bird numbers. Sounds like the numbers of hunters has leveled off or declined and is likely to recover. Ans by the tone of the report they don't seem to have a clue why that has chanced.
Hunters, who require dogs to hunt, have a much longer lead time to get back into a sport. If you are a Dove shooter and stop because numbers are down for a few years, you can get right back into the sport buy buying a few boxes of shells and the appropriate hunting licensees. If you need a dog to hunt it take a year or more of deliberate planning and training to get back into a sport. At some point, many who had dogs who are retired or dead, will get to the point that they will no longer buy and train another as they have found other interest to pursue.