The layoffs last summer tell us all we need to know about the direction Mozilla's headed. I think they're toast. Brave and -- dare I say it? -- even Edge have brighter prospects.
They're all based on chromium though. That gives Google a lot of leverage because every time these projects decide to do something different from upstream it adds to the maintenance burden.
If Google decides to make some fundamental changes to their core engine that would make, say, ad blocking a lot more difficult, would the other chromium-based browsers deep-fork the entire codebase to keep ad blockers working while at the same time integrating the new features as fast as possible in order to remain competitive with Chrome?
Microsoft has the resources to do it, but they may not care. Brave and Vivaldi would almost certainly care, but they may not have the resources to do it.
I could spend all day criticizing Mozilla but I'll use Firefox to the bitter end because of this. In the end there are only three engines in widespread use these days: Chrom(e|ium), WebKit/Safari and Gecko. As far as I know Safari is irrelevant outside of Mac world, so losing Gecko would be terrible for the open web.
Gecko is already effectively lost -- the groups doing cutting-edge work were cut back in August. We're just watching the implosion.
I switched from Firefox to Brave in October and suggest others do the same. Personally, I believe Brave would indeed "deep-fork" the Chromium codebase if necessary, and I'd guess there's a significant chance that other Chromium-based browsers would use it in preference to a submarined upstream.
