With Firefoxes market share continuously declining, and AFAICT no real indication they're going to be able to turn things around, I fear it's only a matter of time before they pull an Edge/Opera and turn into another Chromium reskin to cut costs.
What Firefox needs is to be spun out of Mozilla, to get competent management and a way to directly donate to FF without also ending up sponsoring all of their pet projects.
No doubt open source "firefox" will continue to exists, even if it mean bugfixes only. I plan to use that (Haven't used non-Firefox on Android ever, except by mistake/deception).