I dont sell bikes so the value is not important. The reason the 50s and 60s are not selling is the age of people who can associate with them. From what i see, it is the old typical ride to work bikes struggling to sell but good looking bikes can find buyers.
At least the people who like these old ones can get a better buy for fun.
My old bikes cost 2750 for 1 and 2300 for the other so will not drop right out of value. They get sold after i pop off.