For now it is anyone's guess what these files could contain as WikiLeaks didn't yet provide the decryption key. At a first glance the files seem to be encrypted using AES on 256 bits. For now there's no easy way of brute-forcing these but recent mathematical researches could allow the data to be decrypted by most people in the next 10 years.
WikiLeaks' intention is of course to have some kind of insurance and as they publicly stated on Twitter "from time to time to nullify attempts at prior restraint". Anyone can download the files via torrent files or other mirrors. Some security experts believe this move is a sign that WikiLeaks is preparing for a fight with any government that wants to keep its information out of the public view. Wherever their goal is if WikiLeaks will ever release the decryption keys these encrypted files could be worth a lot.