Seems to me, many areas that had great turkey populations in the 1990's & early 2000's, now have but a fraction what they had, DESPITE now having even better habitat for turkey! And, that habitat is particularly better for nesting success.
Meanwhile, more of TN's annual turkey human hunter harvest seems to be coming from those counties (and portions of counties) that had relatively few turkeys during the 1990's & early 2000's.
So, what gives?
Likely, it is no one thing much more than another,
but all the above mentioned factors play a role in reducing, sometimes even decimating, turkey populations in places with great turkey habitat.
My personal observations include a fast "evolution" in predators "learning" to hunt for turkey.
It may be that in areas with low turkey populations, it takes several years before the predators begin focusing more, and more, on hunting turkeys. I'm talking mainly the predation of poults and adult birds, more than egg raiders. I'm generally seeing pretty good nesting success, followed by much lower survival to adulthood compared to times past.
Along with this, there has been a significant increase in the raptor population, and those raptors have evolved to become more proficient turkey killers. Let a single Cooper's hawk see a hen with young poults, then most of those poults are dead within a few days, as the Cooper's will never let that hen out of his sight until he's done.
Should any survive Mr. Cooper, they next face the larger hawks, as well as the owls, and now even Bald Eagles. This is on top of bobcats and coyotes evolving to focus more and becoming more proficient at killing turkeys as well.
Next, we have had a progressive increase in "feeding" corn, and the aflatoxin poison is taking a toll as well. What's more, these "feeding" stations commonly become "ambush" points for bobcats, coyotes, and maybe a surprise to many, your neighbor's dogs. And, too often, these feeding stations have become where many humans kill their turkeys as well.
My conclusion is increased predation, increased human hunter proficiency (progressively killing a higher percentage of what's available), and increased aflatoxin poisoning are combining to cause population declines even in areas of improved habitat.