Seeing as it's available in Firefox Nightly, it'd imagine it'd be in the next release provided it doesn't present any problems from then and now.

A feature introduced in e.g. Nightly 78 might stay out of stable until say version 86. That is features make it to stable by becoming stable not because it first landed in a certain nightly and so everything was held up until all features in that nightly became stable. Releases happen on a fixed 4 week calendar cycle instead.

Based on https://bugzilla.mozilla.org/show_bug.cgi?id=1563480 I'd say it's probably a good number of releases away.

Here's some context you didn't ask for, but hope you find it helpful.

There's standardization work being done to enable SAB behind a new security context. Mozilla has a good summary: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Refe...

At the moment, I think only Chromium enables SAB by default for devices that have "Site Isolation" enabled (avoids spectre attacks by using process isolation). That's a browser feature specific to Chromium, and is disable for some low-memory devices, so it's not universal.

I'm not familiar with how far along Chromium or Firefox are. If you're interested in using SAB, start reading up on COOP and COEP.

Source: I work on web tooling at Chrome.

Ergo "provided it doesn't present any problems from then and now", but I'm grateful for the context offered by that ticket.

Which is a pity, Firefox has already landed on "nice to have" on our browser matrix, and these kind of decisions don't help.