Really interesting discussion here. Lot's of opinions as to what might be happening in different parts of the country. The fact is, everybody is probably correct to some degree in their individual assessments of the factors impacting turkey populations where they are located. I might as well add my penny's worth...
The bottom line is that, as hunters and conservationists, there are some factors we can have a positive impact on,...and others we cannot. Having a thorough understanding of wild turkey biology, and basing hunting/management decisions on that is one of the things we can control. One of the most obvious is the setting of season dates. The entire premise of spring gobbler hunting is that if you let the turkey population have adequate time to breed before you hunt them, it does not matter how many gobblers you take out of the population afterward. Simply put, spring hunting in properly-timed seasons has no impact on wild turkey populations,...IF (and its a big IF) all/some other factors (environmental factors, habitat, predation, etc.) are not overwhelmingly negative.
Get the right combination of factors for a few springs and turkey populations can skyrocket. Get the wrong combination, and they can plummet. Those, in either case, are almost never associated with human predation/hunting, but the most obvious result of those combinations of either good or bad factors is the quality of our turkey hunting in any given place and year.
Human-induced factors are another matter. Changing agricultural practices, use of pesticides/herbicides that may very well be impacting nesting success and poult survival, introduction of poultry diseases due to the expanding domestic poultry industry, changes in social attitudes about predator control, artificial feeding practices, climatic changes (especially increased spring flooding), etc......all have the potential, singly or in combination, to significantly impact turkey populations.
As far as habitat/carrying capacity goes, the good news is that we are perfectly capable of modifying that for the good,....if there is enough desire to get it done. The bad news is that population recruitment (poult survival) is not so easily accomplished. We have to have some help from nature on that one.