A link to the article?
http://www.chicagotribune.com/classified/automotive/sc-auto-cover-0510-eighties-mercedes-20180427-story.html
I have yet to read the article. The only way that they would hold their value is if they are original or close to original. If Xennial's and Millennial's do not add 20 in rims and keep upgrading the stereo to a minimum the R129 should hold its value.
I was unable to attach the article or the picture of the article.