> The only chance I see for Firefox is doubling down on that and replacing more and more components with those Rust rewrites
If Firefox has no more Rust developers now, it can't "double down" on replacing components, and all software is prone to bitrot, so after a few years, it will be an unmaintainable, buggy mess.
Mozilla did lay off most of its employees that were working directly on the Rust language and its implementation. This was a handful of people.
Mozilla also laid off some employees that were using Rust, such as the Servo team.
But Mozilla still has plenty of employees that know and use Rust, both in Firefox (e.g. the WebRender team), and in code relating to Firefox such as services. This is a much larger number of people.
My understanding is that there is still plans for more Rust in Firefox.