I have a theory regarding the box that was in the season premiere, and how it is to be opened.
This could contain major spoilers, so be warned.
The Mane 6 gave up their elements in the beginning of the series. I think that they may be able to get them back or get replacements for them. Throughout the course of Season 4, the ponies have been going about their lives, having their adventures, and doing nothing to reach the goal of opening the box. So it seems.
First off, I really really like the episode 'Pinkie Pride'. Pinkie is my favorite pony, and I really like the songs in the episode. I've seen it more times than I can count (I lost