What's a few years? They go by in the blink of an eye. Zig is a perfectly usable language. People who want to use it will, those who don't won't.
it's completely feasible to stick to something that works for you, and only update/port/rewrite when it makes sense.
what matters is the overall cost.
I would expect fixing an application to an older version would be just fine, so long as you don't need newer language features. If newer language features are a requirement, I would expect that would drive refactoring or selecting a different implementation language entirely if refactoring would prove to be too onerous.
how about you goes to Zig github and check how progress of the language
it literally there and its still beta test and not fit for production let alone have mature ecosystem