It's not extinct and won't go extinct. It doesn't live in its natural range but there are wild stands outside which haven't been exposed to chestnut blight, and there's a genetically engineered variety which is resistant to the disease and which may be released into the wild soon.
Thank goodness for that. I heard there is a French variety that comes to crop within about twelve years, that also has resistance to chestnut blight. I was pleased, very pleased.