Here's a cool concept created by Ko Yang: a carton that morphs its design overtime using color-changing ink. It can be done but, most probably, it will never be used in real life—most companies don't want people to skip their older merchandise at the supermarket.
Or perhaps some companies would end up doing it, to highlight their compromise with freshness or some other marketing point. But it's a great, elegant idea in any case. The only way this could be cooler is if the package always said "It's time to throw me away!" out loud (now that would be really awesome.)
p.s. The idea is not new—Yanko Design first posted about it in 2008, but people are all in awe about it now since it was posted without attribution in Reddit.