Value of a National Geographic dated December 1969 in 2016?

The December, 1969 issue of National Geographic Magazine is worth $500 US at a minimum if the issue's enclosed record has not been removed and is undamaged, and the entire magazine has only average wear, including minor binding wear at the end of the spine of less than 1/4 in on each end. This minimal value is the result of the tragic passing of Neil Armstrong, the first human being to walk on the surface of the Moon.

Professional collectors, though, suggest that individuals hold on to their copies of this issue of the magazine. They are in almost unanimous agreement that the value will exceed $1000 US within the next six months, by the spring of 2013.

I suggest that individuals retain this invaluable piece of American history, and not sell it, in order to pass it down to their family members and future generations.