The next priorities will be to make the image installable, and to improve how rustc runs on Redox (for self-hosting). After that, it will be easier to develop on Redox OS and work on porting larger pieces of software like Firefox.

Why not Servo?

Servo never made it to a place where it could consistently render most websites correctly. People underestimate the amount of work required to get something like that production ready by several orders of magnitude.

I'd love to port Servo, but the first thing people would ask after doing that, is probably when is Firefox going to be ported ;-)

I'll cast another vote for Servo. Serenity has their own native browser: https://github.com/SerenityOS/serenity/tree/master/Userland/...