Well, all he
said was '“Those subtitles… they start to give little bits of hints about maybe what’s going to happen", I didn't interpret that as the subtitle involving some big reveal.
I do think they could've revealed it in E3 2021, a trailer that showed both [tear]drops and an ancient civilization. To me the title indicates a shift in direction away from the 'wild' (the fallen world of Hyrule reclaimed by wilderness) to the 'kingdom' - meaning both Hyrule rebuilt and the ancient kingdom in the sky.
Honestly when Bill made that comment they might not have even had a name yet, possibly deciding between names.
(I often feel like I'm the only one who likes this title
)