I'm not sure that there's any way to future-proof yourself short of printing information on archival-quality paper and then securing the paper somehow.

My concerns with TrueCrypt are twofold. It hasn't been meaningfully updated since February 2012. If any vulnerabilities have been discovered since then, they haven't been patched.

Secondly, there is speculation that the withdrawal of the product may have been due to pressure to introduce vulnerabilities deliberately. That's speculation, rather than based on hard fact, but it is very troubling. Historically, whenever vulnerabilities are deliberately introduced they are discovered by the people that you don't want to have them.