Earlier quoted context omitted.
Tweets from Google employees who work on chrome: https://twitter.com/estark37/status/1422694855390629893 https://twitter.com/domenic/status/1422647331804037120 https://twitter.com/domenic/status/1422647483944034308 https://twitter.com/domenic/status/1422704005453582337
Those links contradict your assertion, instead indicating a move to "non-blocking alert()"
> Yeah, I think the most likely eventual "removal" path is actually non-blocking alert(). (confirm() and prompt() cannot be converted to non-blocking though, so they'd have to be fully removed)
Blocking Javascript execution is a fundamental part of the `alert` spec. Replacing it with a different, non-JS-blocking thing that happens to share the same name doesn't mean that `alert` wouldn't be removed as it exists today.
And there's just no way at all to make `prompt`/`confirm` non-blocking, they have to block the main JS thread in order to keep the same API.