Crayola’s Law states that the number of colors of crayons doubles every 28 years and most people are able to distinguish about 1 million colors. These two facts mean that the number of crayons will exceed the number of recognizable colors around the year 2362. If you are one of those rare individuals with tetrachromacy then you are safe until between 2530 and 2558. By the way, in 2362 a box of crayons will weigh 5.4 tons.
For more information on Crayola crayons see List of Crayola crayon colors.