I was thinking the private keys could be encoded in an encoding language to make them slightly extra secure incase any thief has no idea what he's doing.
I think what actually you're looking for is Obfuscation[1]. But generally it's not recommended due to risk of forget or unable to extract the data.
I would love to just be able to store my holy wallet.dat file away for many years and be able to re-gain access to my wallet using this file, primarily through other wallets too if Bitcoin Core wallet seizes to exist by then.
That should never happen considering that bitcoin core is the reference implementation of Bitcoin. But it is open source and many people are using it, so it would be trivial to write a simple script that decrypts and extracts the keys inside the wallet file to be used elsewhere.
Additionally you could also,
1. Backup Bitcoin Core.
2. Rely on public archive such as
https://archive.org/details/software.
2. Ask someone else who have such file, since many enthusiast run Bitcoin Core.