This was an example question. The problem is wide, that's why I was asking about _forward compatibility_. Even if I have long term support, what happens if tha

This was an example question. The problem is wide, that's why I was asking about _forward compatibility_. Even if I have long term support, what happens if that runs out? How does that work in the presence of scripting and extensions? TeX has a whole culture around that - even if there are no long term releases, it is _very stable_. For example, the LPPL even prohibited releasing changed files under the same name for a long time! https://en.wikipedia.org/wiki/LaTeX_Project_Public_License https://en.wikipedia.org/wiki/LaTeX_Project_Public_License