If it becomes a collectors item, the threaded barrel will cut the value in half.
If it doesn't become a collectors item the threaded barrel will increase the value to someone who wants a threaded barrel.
If I had a crystal ball and knew what guns were to become a collectors item I would plan my gun purchases and sales much differently. Since I don't have a crystal ball, I set my guns up the way I want to for what I use them for and don't worry about a future I can't control.
"If your plan is for one year, plant rice.
If your plan is for ten years, plant trees.
If your plan is for one hundred years, educate children."