To the people here proposing a “wait and see” approach: what do you think we should be looking for?
Inline arrays are not a novel feature. C, C++, Rust, Go, and Zig all have inline arrays, and there’s no reason to believe that inline arrays would be used differently in Swift than in those languages. From those other languages, we already know the likely usage patterns of InlineArray.
More specifically, we know that the amount of usage inline arrays get heavily depends on the work being done. They’re heavily used in performance-sensitive code and cryptography, but other contexts might not need them at all. Different people will have different experiences with the type and come to their own conclusions about whether sugar would be worth it. The idea that, later, we’ll be able to come together and all agree on whether a sugar is worth it is ill-conceived.
I don’t expect deferring the decision to add sugar to InlineArray to help us very much, if at all. I believe it would just defer this debate to the future, and that we’d see the exact same arguments being made then as are being made now. It would have the detrimental effect on documentation, tutorials, talks, style guides, and examples that Doug Gregor described, without much benefit.