Why? Servo is just a proof of concept, it won't be the future of Firefox.
> Our long-term plan is to:
> - Incrementally replace components in Gecko with ones written in Rust and shared with Servo.
> - Determine product opportunities for a standalone Servo browser or embeddable library (e.g., for Android).
Check the "Oxidation" page on the wiki: https://wiki.mozilla.org/Oxidation