How can I "future-proof" my LaTeX documents so that they can be re-compiled at a later date?
One solution you might want to consider is compiling your own format that includes all the packages you are using and keeping this special compiled format with your latex file. In this case, when packages get updated, you will still maintain the same state that you have now.
You can read about compiling styles here:
- Using mylatexformat with this how to, probably the easiest and least disruptive to your actual document file.
- This post, which requires to split your document into a static preamble and dynamic contents.
The good news is that, once you start compiling your preamble this way, you will tremendously save on compilation time of the document. This is the glorious of this technique. (I personalize use that, with externalization for tikz graphics and I can compile very complicated journal papers in less than 10s).
If you really feel paranoid about it, you might want to keep a snapshot of your tex and latex binaries along with their fonts.