You claim it's dead, but suggest using a fork that can't hope to keep up if Firefox dies? They benefit from all the architectural improvements done to Firefox, including this.
The repo's members page [0] shows 9 users, and the first bullet point on its features page [1] is: LibreWolf is compiled directly from the latest build of Firefox Stable. You will have the the latest features, and security updates.. You believe a small group of well-intentioned volunteers can continue the work of building and iterating a modern web browser were Firefox development to end today?
No, it's not. Mozilla has 750 employees (not all of whom work on the browser, but still) and hundreds of millions of dollars and they're constantly struggling to keep up with Chrome. 9 part-time devs cannot do this.
We're talking about different things. I'm sure the LibreWolf team could develop a browser that meets some specifications and renders some websites some of the time. What they can't build is a Chrome competitor. It would become an often-broken hobby project only used by enthusiasts, like the others you've listed.
Otter and qutebrowser are based on QtWebEngine which is a wrapper around Blink (Chromium's engine), Min is using Electron which is also a wrapper around Blink, surf uses WebKitGTK which is a wrapper around WebKit (Safari's engine) and Bromite actually says is a Chromium's fork. The contributors for those browsers have to only maintain the GUI which is just the tip of the iceberg. As for Links, it cannot render most of the web.
Basilisk and its sibling Pale Moon are an example of how hard a fork is (both being pre-Quantum Firefox); features removed because cannot be maintained, incompatibilities, poor performance and many vulnerabilities.
Did you know that I can still use a web browser from the last decade to surf websites? Yup.
Even if FF dies, the codebase is opensource and continue to be developed.