The data from Wilhelm must be considered from many aspects. He uses 500 FC for fading in most cases just like Fuji, but Kodak uses 100 FC, which is the level measured in most homes as an average of 10,000 or so tests run world wide. This level difference represents reciprocity in fading which is just as real as speed or contrast reciprocity.
Also, note that the figure of faded transparencies in a Florida airport are not shown in color but it states that they have faded substantially. Do we take that on faith or can we see the original color shot of that display....
Do not take everything from Wilhelm at face value, there are many points of view on this subject. Not least of which, I might mention, relate to air pollution effects and Ozone / UV radiation levels.
Bottom line is that we will not know for sure for about 200 years.