I'm a bit late to this conversation but I wanted to drop in and support this comment. I live in North Carolina and have personally seen dozens of adolescent American Chestnut trees in the Appalachians in the western part of the state. They love the high ridge lines out there. Most of the chestnuts I've seen look like shrubs due to how they develop and can easily be missed of you're not looking carefully for them. From what I've read elsewhere most American Chestnuts only make it to 5-10 years old before the blight gets them. I've only seen a couple of trees taller than 10-15' tall in the wild (and have seen several infected with the blight).
The American Chestnut is "functionally extinct", because despite the fact that they are somewhat prominent throughout their native habitat as adolescents, they rarely (if ever) are able reach maturity and develop fruit (and therefore can't reproduce).
Here are a few pics of some adolescent chestnuts if anyone is curious:
- https://unsplash.com/photos/O9q1p_9bji0
- https://unsplash.com/photos/0s7_4fm8y-g