Servo wasn't even the main engine.

Considering their main revenue sources will likely be decimated, it makes sense to focus resources on the primary browser engine, and allow the open source community to build out the experimental features, moving temporary resources there as needed.

The thing with Open Source is that even if Mozilla Corp goes under, all of us can continue building out Firefox like a regular open source project. Or the Linux foundation could pick it up, etc.

That's literally how Firefox was created in the first place, as an open source continuation of the Netscape browser.

Using Firefox will lead to improvements that will persist even beyond Mozilla Corp. In the meanwhile, Mozilla Corp can be looked at as an experiment to commercially and profitably develop Firefox, which, if it fails, will require us to switch to the non commercial models that are driving several other open source projects.

The way to guarantee a future without an alternative browser is to not use an alternative browser.

I hear you, but simultaneously everyone (including me) has a certain limit to which they will be principled. If it happens like I mentioned, I will jump ship. On macOS, Firefox still guzzles battery compared to Chromium browsers. This seemed like a thing that, whilst not fixed, was actively being worked on. If I had to hazard a guess, that will slip heavily in priority now.

Who knows. The best way to vote is to be an active user of the product and give feedback that power use should be a priority.