Competition is good. Nobody wants to be left behind by Google, so time for Apple and MS to step it up again.
Firefox is still using Gecko, and is working with Samsung on a long term effort to develop a new engine (Servo) in Rust.
You may be thinking of the recent news that Opera is using WebKit, but even when that was first report it was identified that they were really basing on Chromium rather than WebKit proper, and they've announced (in this thread, even) that with Chromium moving to Blink, Opera is following.