> Realistically how much of a problem is this likely to be?

It is a very young language with momentum and a foundation behind it. I'm not aware of any pre 1.0 stability guarantees.

In fact it is generally recommended to use the nightly release (see: https://ziglang.org/learn/getting-started/) because they are moving quickly.

Definitely seems to be in a early adopters and tinkerers phase.