What do you guys think? Do you think there will ever be a security flaw within the implementation of the Zip encryption or early versions of Electrum?
That is very doubtful. Both Electrum and the Zip Archiver use advanced encryption algorithms that are considered to be very secure. The biggest weakness in your setup is likely the password strength for both the Electrum wallet and the Zip archive. If you used weak or short passwords, those should be your primary focus for breaking the protection. But know that brute-forcing a password can take a lot of time and computer resources, depending on the password length and complexity. The more you remember about those passwords - length, any special characters, if you used any words or phrases, etc. - the better your chances. Every little detail helps, but there's no guarantee of success.