Doing the future totally goes out of the "culture and historical significance" zone, since you're just trying to predict what could happen. And the video itself would end up being no different than if you did it for another decade in a past century without actually trying to make something interesting. What are you going to do, show spaceships in late 2100 instead of trains in late 1800? I'd expect something more original from the finalists...
I'll just leave you with something to think about: godix said somewhere (can't find where it was) that he believed Skittles was inspired by 60s ads/pop-art. Now, I'm not sure if Koop ever confirmed or denied this, but try to take the history and culture to wider meanings. For example, if I were to do a video about Italy in the 30s, I'd totally ignore the fascism and try to represent Istituto Luce and Cinecittà by making a video that represents how the introduction of cinema in the country actually affected the decade itself and the decades to come, too.
Please do think outside the box, you're finalists. Theme limits are only limits if you make them be so, you should take them as an enhancement to furthen your competitive spirit and work harder to get better ideas out there. I mean, people say the Nuzlocke Challenge is better than a normal playthrough, so that must mean something.
Like MimS, I'd obviously love to see better videos. But I don't think easening the theme challenge would be a solution. At most I'd give out extra time to work the theme out, but I don't think it's a necessity. I mean, the best videos would be made if we gave complete freedom with a "do whatever you want" theme, but what's the challange anymore? It's not Project Editor for nothing.